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Institute of Food and Agricultural Sciences
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________________________________________________ Institute of Food and Agricultural Sciences |
Southwest Florida Vegetable Newsletter
March / April 2001
May 14-18 2001
Aquatic Weed Control Short Course 2001,
Fort Lauderdale Research and Education Center and Fort Lauderdale Marriott
North.
For more information contact Beth Miller Tipton at (352) 392-5930 or
E-mail bamt@gnv.ifas.ufl.edu
or visit their web site at www.ifas.ufl.edu/~conferweb/aw/
May 15, 2001
Gulf Coast Research and Education Center Vegetable Field Day,
Bradennton, FL.
Contact Don Maynard at 941-751-7636 x239 or dnma@mail.ifas.ufl.edu
May 17, 2001
Spring Vegetable Field Day and Pest and Disease Scouting Workshop,
Southwest Florida Research and Education Center,
Immokalee, Florida.
For information, contact 863-674-4092
June 6, 2001
KaPam/VaPam Certification Course,
Southwest Florida Research and Education Center,
Immokalee, Florida.
For information, contact 863-674-4092
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Gene McAvoy
Vegetable Extension Agent II Hendry County Extension Office PO Box 68 LaBelle, Florida, 33975 863-674-4092 |
What a roller coaster this season has been! Freeze, drought, tomato prices in the pits ……
Despite all of this, vegetable producers are a stalwart bunch with a large capacity for risk and are not easily sidetracked by adversity. As we all know certain risks are unavoidable, weather related events are acts of God and must be dealt with in the best way possible as they occur.
Although markets and prices are determined by the forces of supply and demand, and are generally beyond the control of any grower or particular group, one has to wonder how often one must bang their head against a brick wall before they are able to grasp the underlying message. To be sure, the environment has changed dramatically over the past decade and foreign competition has radically altered the equation, but this situation is not likely to change and will probably intensify in the years ahead. The take-home message is that we must seek new ways of doing business, particularly where it comes to marketing.
Consumers are looking for diversity and other qualities in the produce they purchase for consumption. Green, gassed tomatoes have been relegated to the level of commodities for mass market outlets while sophisticated modern consumers are willing to pay premium prices for vine-ripened tomatoes and other characteristics that they are seeking. The current market success of greenhouse produce from such diverse places as Canada, Holland and Israel is mute testimony to this fact.
Even locally, one can point to entrepreneurial growers that have successfully gone in new directions in terms of crops and marketing outlets.
You won’t hear many of this sort complain of low prices because their reality is quite different than the bargain basement situation plaguing many growers.
Without a doubt, change will not be easy and some larger growers may continue to compete successfully on the basis of their size and ability to spread risk across multiple production areas and growing seasons. For many other change is probable the only guarantee of future survival.
For the vegetable industry to survive the transition rocking the industry, cooperation between al entities will be critical.
New varieties combining the traits the market seeks with adaptability to our growing conditions will have to be identified. Consumer pressure will also demand that production technology reaches new levels of environmental awareness.
As in the past, research and extension will play a critical role in this process. Therefore it will be essential that all the players in this industry engage in meaningful communication so the process of change occurs smoothly and as painlessly as possible.
I sincerely believe it is possible, how
about you?
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These tips will help you to start an IPM program or make your current program work better for you.
Why should you monitor your plants?
Conducting frequent visual inspections of your plants and crops gives you a good indication of pest activity and population, provides you with up to date information on the health of your plants, and allows you to make proper pest management decisions. When monitoring, you should check often for insect pests, weeds, disease, weather damage, or nutrient deficiencies that may kill or stunt the growth of your plants.
An effective monitoring program also includes keeping accurate written data on soil types, fertility levels, history of pest problems including the exact timing, and location of each pest occurrence and past control measures. You can keep track of weather conditions by using on-site weather stations or various local weather service. Understanding climatic conditions can help you determine why certain pest problems are occurring.
In the long run, monitoring can save you money on pesticides by allowing you to make better decisions on when to spray or not to spray.
The importance of checking your soil
IPM monitoring includes making frequent checks of soil conditions. Soil lacking in nutrients, pH and other factors will not be able to support plants. Conducting tests on soil samples will help you determine if it is necessary to apply fertilizer, lime or other chemicals.
Before taking soil samples in a field keep in mind that your soil will probably not be the same in all areas. There could be differences in soil texture, appearance, wetness or salt content. Therefore, you should break your field down into smaller areas with similar soil conditions, then randomly take 15 to 20 samples from each area. The test results should help you determine the deficiencies in your soil and what action you should take. Be sure to keep a written record of the area where each soil sample was taken for future use.
Another factor to consider is compaction, in which soil pores are reduced in size by heavy foot traffic, equipment, or excessive rainfall, robbing plants of the air, water and fertilizers they need in order to grow. You can reduce compaction by never working in wet soil, varying the cultivation depth each year, installing flotation tires, dual tires or tracks on equipment, and using shrubs, mulch or fences as borders to reduce foot traffic.
Using insect traps
The use of insect traps can help you determine the number of pests that may be present. There are several types of traps including pheromone traps in which sexually attractive odors are used to lure male insects, "sticky" traps, "visual" traps that attract certain insects by their color and shape, and black light traps.
Insect traps offer several advantages:
1. They work 24 hours a day.
2. They indicate problem areas
where pests are present so you don't have to treat all of your plants.
3. They help you decide the
best possible time to apply pesticides for maximum effectiveness.
4. They may reduce your use
of pesticides, which can mean lower operating costs and a reduction
in health risks and liability if your employees or neighbors
are exposed to harmful chemicals.
Using sweep nets
Another effective tool that can help determine the extent of insect pest problems on your plants is the sweep net. Sweep nets look like butterfly or fishing nets, only the handle is longer and the net is made of more heavy duty material (normally cotton muslin or sailcloth). The net is swept back and forth, and the insects captured in the net are counted to determine if the levels present indicate a need to apply pesticides.
Sweep nets can be used to capture various insects such as weevils, leafhoppers, stink bugs and aphids that may be present on crops including alfalfa, blueberries, carrots, cotton, potatoes, soybean and wheat.
IPM Almanac
http://www.ipmalmanac.com/tipsheets/tip16.as
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Production systems for watermelon are diverse. While dryland and bare ground production can still be found, plasticulture (the joint use of plastic mulch and drip irrigation) is becoming popular. The production of high value 'seedless' (triploid) watermelon is almost exclusively done with plasticulture. Property managing water and nutrients is an essential component of successful commercial watermelon production. Fertigation (the application of soluble fertilizer through the drip tape) allows to best control water and nutrient applications to vegetable crops, including watermelon.
The objectives of this article are to describe watermelon water and nutrient needs and outline current IFAS recommendations for watermelon production. The complete watermelon production guide can be found in Chapter 26 of the 2000 edition of the UF/IFAS 'Vegetable Production Guide for Florida’ also available online at http://edis.ifas.ufl.edu/CV123. Additional information on principles of vegetable fertilization may be found at http://edis.ifas.ufl.edu/CV009 .
Watermelon Water and Nutrient Needs
Excessive water supply (from rain or irrigation) will leach mobile nutrients (primarily nitrate nitrogen and potassium) below the root zone. As a general rule, soil water tension in the root zone should be maintained between 8 and 15 centibars to ensure adequate moisture level. Soil water tension (as an estimate of available moisture) can easily be measured in the field with tensiometers, gypsum blocks or similar devices.
Watermelon water needs depend on stage of growth and rainfall. Current IFAS recommendation is to apply 20, 40, 70 and 90% of reference evapotranspiration (ETo) during 1-2 weeks after emergence (WEA; early growth), 3-6 WEA (rapid growth and development), 7-9 WEA (peak growth and fruit sizing), and 10-13 WEA (late season to harvest), respectively. Because the sandy soils used for watermelon production have a low water holding capacity (8 to 12%), irrigation is applied once daily, sometimes twice.
A common misconception exists about the efficacy of rainfall in supplying water to mulched watermelon. Although heavy rains are common in Florida during production season, two factors make rainfall almost non usable by the plant when plasticulture is used. First, the plastic mulch shields the row, thereby greatly reducing the amount of rain that can reach the root zone directly. Rainwater in the row middles is not very efficient either, because lateral movement is limited to few inches in coarse textured soil.
Consequently, plastic mulched watermelon may still need to be irrigated despite heavy rains.
Watermelon plants need 16 essential nutrients to complete normally their life cycle, and thereby produce marketable fruits. These 16 essential nutrients may be categorized into three groups. First, carbon (C), hydrogen (H) and oxygen (O) are supplied mainly by atmospheric carbon dioxide and water. Then, nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), and sulfur (S) are the macronutrients. These elements are called 'macronutrients' because they represent between 0.2% to 7.0% of the dry matter. Finally, boron (B), copper (Cu), chlorine (Cl), iron (Fe), manganese (Mn), molybdenum (Mo), and zinc (Zn) are the micronutrients.
Micronutrients are present in plants in small quantities (from less than 1 to 500 mg/kg dry matter). Yet, the micronutrients are as essential as the macronutrients. Terms such as 'minor' elements misleadingly suggest they are not important. Therefore, these terms should be avoided. In watermelon production, the essential objective of the fertility program is to ensure that mineral nutrition is adequate and is unlikely to limit yield.
In a typical fertilizer program, most N, all P, most K most Ca, all Mg, all S, and micronutrients are applied preplant. The remaining N, K and Ca are applied though the drip tape. Typical N sources are ammonium nitrate, potassium nitrate, and calcium nitrate.
For fast growing vegetable crops, two additional concepts are important for proper fertility: nutrient availability and uptake patterns. First, an essential element's presence in the soil (following application or endogenous) has no correlation with plant availability. That is because soil pH (as expressed by acidity or alkalinity) chemically controls availability. For example, Fe chlorosis is common when soil pH exceeds 8.2, while total Fe level in the soil may be 1 to 2%. At alkaline pHs, Fe forms Fe(OH)3 which is insoluble. Similarly, chemical combination of P with aluminum (Al) or Ca reduces P availability for uptake at low pH. Therefore, maintaining pH within the optimal range is part of a fertilizer program.
Liming is the cultural practice that aims at maintaining soil pH within the desirable range. For watermelon, this range is 6.0 to 6.5. Soil pH and lime requirement can be easily determined by soil testing. The most common liming material used in vegetable production are calcite (CaC03) and dolomite (CaC03-MgC03). It is important to notice that it is chemical reactions involving C03 that modify soil pH. It is sometimes incorrectly believed that it is Ca that reduces the pH. Sources of calcium such as calcium nitrate or gypsum (calcium sulphate) have no significant impact on soil pH, and cannot be used as liming materials.
The second important concept in watermelon fertility is that what watermelon plants need for each essential nutrient is not uniform and varies during plant growth and development. Fertigation allows producers to adjust amount injected to plant needs. Current IFAS recommendations for watermelon are to inject daily l.0, 1.5, 2.5, 1.5, and 1.0 lbs of N and K20 for 1-2 WAP, 3-4 WAP, 5-9 WAP, 10-13 WAP, and 14-16 WAP, respectively. These recommendations are based on a 8 foot spacing, and should be adjusted as needed when different spacings are used.
The only way to satisfy plant nutritional needs is to develop a fertility program based on a calibrated soil test. A calibrated soil test reveals the amount of plant available residual fertilizer, which is used to issue a fertilizer recommendation. A calibrated soil test also reveals soil pH and soil buffer pH, which are used to issue a lime requirement recommendation. The proper extractant for acidic, mineral soils of Florida where most watermelons are grown is the Mehlic-1 extractant.
As every growing situation is different, and as
weather conditions vary from year to year, watermelon plant response to
the same fertilization program may vary. Therefore, it is necessary
to monitor plant nutritional status during the crop. This can be
routinely accomplished either by leaf sampling and foliar analysis, or
petiole sap testing. Threshold values are available for optimum
leaf and sap nutrient content for watermelons in the watermelon production
guide. With fast laboratory turn around (less than 48 hours) or field
measurements, the results of foliar analysis and/or sap testing can be
used as management tools to adjust fertilizer applications to each growing
condition.
Blossom-end Rot: Can Be Avoided
The lack of any of the essential element induces the development of characteristic nutritional disorder symptoms. While shortage of any nutrient reduces yield, only one common disorder-blossom-end rot (BER)- will be discussed here as it clearly involves an essential nutrient (Ca) and water.
BER is an irreversible browning of the blossom-end of the watermelon fruit. It is caused by an insufficient calcium supply to the fruit. Low calcium may be due (1) to low calcium levels in the soil, or (2) reduced movement of calcium into the growing fruit. As calcium is transported to the fruit by the transpirational stream, reduced transpiration-caused by low moisture or weather conditions not conducive to transpiration such as cold, cloudy days-will reduce calcium levels, thereby inducing blossom-end rot.
Watermelon fruits cease to transpire (cease to allow water to evaporate through its cuticule) when they reach the size of an olive. As transpiration ceases, water transported to the fruit is not lost through transpiration, thereby allowing the fruit to enlarge. Therefore, adequate calcium levels must be translocated to the fruit while it is still smaller than the size of an olive and still transpires.
The brown color associated to BER is due to a series of chemical reactions in the watermelon fruit due to breakage of cell compartments caused by a lack of calcium. As it reflects structural damage at the cellular level, BER is irreversible. Attempts to add calcium to the soil as dry fertilizer or to the leaf as liquid foliar feed to BER affected watermelons are usually inefficient and are unlikely to reverse the disorder.
In conclusion, successful watermelon production requires simultaneous management of water and nutrients. Such management is easiest when drip irrigation is used, but possible with all production systems. The foundation of a proper water management program is the measurement of soil water tension. The backbone of a sound fertilization program is a calibrated soil test, complemented as needed with foliar analysis or petiole sap testing. In all cases, IFAS recommendations should be followed.
Dr Eric Simone
Citrus & Vegetable Magazine
March 2001
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The Web site has something for everybody consumers, retailers, media and industry members. The site even has an area dedicated to kids and teachers that contains lesson plans and educational games. The NWPB strives to help consumers by providing information such as how to pick a watermelon, how to safely handle and store it, and fun and easy tips such as the easiest was to de-seed a watermelon.
The NWPB is focused on helping everyone understand
the benefits of eating a healthy diet. The "Health and Wellness"
section of the site provides valuable information about the nutritional
benefits of watermelon and how it fits into a healthy diet. To help
visitors understand the benefits of a healthy diet, information on the
5-A-Day program and the food pyramid is available.
By entering their e-mail address on the
main page of the site, visitors may sign up to receive the board's monthly
electronic newsletter, the Melon Monitor. After only six months, the Melon
Monitor has more than 8,500 subscribers. Subscribers receive information
about the nutrition and health benefits of watermelon, recipe and menu
ideas and chances to win prizes by entering contests such as a Halloween
watermelon carving contest and recipe competitions.
Citrus & Vegetable Magazine
March 2001
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In the end, methyl bromide production is likely to continue even if major agriculture uses (85% of the current market) are lost. Methyl bromide is not difficult or expensive to produce, and it is often a byproduct or intermediate for other industrial processes.
Georgia Pest Management Newsletter
March 2001
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The U.S. EPA may accelerate decisions based on cumulative risk assessments. The cumulative assessment is an evaluation of a group of pesticides with a similar toxic mode of action. For example, the organophosphate (OP) insecticides all affect the nerve enzyme, acetyl cholinesterase. Both insects and humans depend upon the same enzyme.
Until now, the agency has made decisions based on the risk estimates associated with a single OP individually. As you have seen, some of the decisions will have tremendous impacts. Imagine how the impacts may increase as EPA considers all of the OP insecticides together. Your commodity needs a crop profile and PMSP!
The Agency is under some pressure to resolve the cumulative assessment. The evaluations completed for individual OP insecticides will not ‘count’ until the cumulative assessment is complete for the OP insecticides. The EPA needs to make decisions. Your commodity needs a crop profile and PMSP!
Finally, integrated pest management (IPM) is clearly the future. The USDA, EPA, and other agencies support IPM. Therefore, pesticides with a role in IPM are more likely to receive favorable treatment. However, a solid explanation is critical. ‘IPM’ is an EPA buzzword. Almost every document contains the words, ‘and this product [insert pesticide name] is critical for IPM programs’. Understandably, folks have become quite cynical about that phrase. Keep in mind that the current definition of ‘IPM’ includes an element that minimizes pesticide risks.
Here is the latest schedule of EPA pesticide activities. In Fiscal year 2001 (FY 2001 ends Oct. 1, 2001), the EPA plans to issue Reregistration Eligibility Decisions (RED) for:
Cacodylic
Acid
Molinate
Endosulfan
Propargite
Ethion
Thiabendazole
Meethanearsonic
Acid
Thiram
The EPA will issue an IRED (Interim RED) in FY 2001 for:
Acephate
Malathion
Azinphos
methyl
Methamidophos
Chlorpurifos
Methidathion
DDVP
Methyl Parathion
Diazinon
Naled
Dicrotophos
Oxydemeton methyl
Dimethoate
Phosmet
Disulfoton
Pirimiphos methyl
Ethoprop
Terbufos
Fenamiphos
A final RED cannot be issued for any of these OP pesticides until the cumulative risk assessment is complete. The IRED may include risk reduction measures or eliminating registrations that the registrant does not plan to support. In some cases, the registrant has agreed to eliminate a pesticide registration that was critical for some minor crop or use. Make sure that the pesticide company, the USDA, and EPA understand why particular pesticides are critical. Your commodity needs a crop profile and PMSP!
The EPA plans to issue TREDs (I don’t know what the ‘T’ stands for) for:
Butlyate
Sodium Hypochlorite
Chlorpyrifos
Sulfur
Citric
Acid
Tetrachlorvinphoos
Limonene
Trichlorfon
Phosalone
Tridiphane
A TRED may be issued for a pesticide registered after Nov. 1, 1984 (pesticides registered earlier are subject to reregistration under FIFRA ’88); for a pesticide with a RED compledted before passage of FQPA; or for a pesticde not registered in the U.S. with a tolerance that allows import of foreign commodities.
Be active early in the process. Your commodity needs a crop profile and PMSD!
You may more information about REDs, IREDs, TREDs, and RETREDs (OK, I made up that one) at the EPA web site, http://www.epa.gov/pesticides
Georgia Pest Management Newsletter
March 2001
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A PMSP is the next step beyond a crop profile. Do not underestimate the importance of crop profiles and PMSP. Without this information, EPA will make pesticide decisions that affect Florida with, at best, information from other states.
Georgia Pest Management Newsletter
March 2001
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At the WPS session held in California late last year, worker advocacy groups came out in force and showed little interest in compromise. That's all the more reason for making sure the Orlando meetings put Florida growers' WPS experiences on the record.
FFVAs Environmental & Pest Management Division is helping to present a one day seminar focusing on the Food Quality Protection Act, Tuesday, May 15, 2001, in the Orlando area. The popular Agricultural Environmental Seminar follows on May 16 and 17. These meetings are among the most concise and useful available on crop protection topics. All growers, regardless of FFVA membership status, are encouraged to attend. Call FFVA for more information at 407-894-1351 or email us at info@ffva.com
Citrus & Vegetable Magazine
March 2001
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“Developments in the past 25 years have shown how conventional agriculture can be much more sustainable and environmentally friendly than organic farming. A single treatment with innouous herbicide, coupled with no-till conventional farming, avoids this damage [increased erosion] and retains organic material in the soil surface.”
The Georgia Pest Management Newsletter
April 2001
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UF/IFAS Vegetarian Newsletter
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Additionally, registrants are encouraged to replace the current phrase ‘Statement of practical treatment’ with ‘First Aid’. Other changes include the use of current medical information, reference to poison control centers, instructions to contact lens wearers and hotline telephone numbers. The presentation format of the information will also be changed to make first aid instructions clearer and easier to find.
For more information, contact Amy Breedlove at 703-306-9069 or breedlove.amy@epa.gov
The Georgia Pest Management Newsletter
April 2001
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Over the past three seasons, powdery mildew, caused by the fungus (Sphaerotheca fuliginea), has become a more important foliar disease of watermelon. Prior to 1998, powdery mildew of watermelon had been reported occasionally from southern states. Between 1970 and 1998, I had seen the disease in Central Florida only a couple of times during extremely dry seasons and, even then, fungicide applications were not needed. In 1998, powdery mildew of watermelon developed early throughout Central Florida and was severe. This resulted in rapid defoliation of vines, reduced fruit numbers per acre, and small, poor-quality fruit. Over the last three years, powdery mildew has been severe in several of the warm-climate production areas of the U.S. The initial field symptoms of powdery mildew of watermelon include small clusters of plants with yellow leaves at the crown. Close inspection of these plants reveals older leaves with numerous chlorotic spots and the characteristic white mold of powdery mildew infection on both sides of the leaf. Unlike most other foliar diseases, powdery mildew may occur during dry weather, since the causal fungus does not require rainfall or long dew periods for infection and spread.
Cultural practices, such as wider plant spacing to reduce canopy density or avoidance of overhead irrigation to reduce leaf wetness periods, can reduce downy mildew incidence and severity, but the principal control for both downy mildew and powdery mildew of watermelon is fungicides. Although downy mildew is not a serious problem every year in watermelons, some preventive fungicide applications should be made because of the rapidity with which downy mildew can defoliate watermelons. With the increase in powdery mildew in watermelons since 1998, fields should be scouted frequently and a spray program should be directed toward this disease when it occurs. Two new groups of disease control agents are becoming available for the control of watermelon diseases. These are the strobilurins, which are effective against gummy stem blight, and plant defense activators, which activate the plant’s resistance mechanism. We have evaluated these two new groups of control agents, along with other labeled fungicides, for the control of downy mildew and powdery mildew of watermelon.
In our evaluations, one or two transplant house applications of Actigard at 0.05 g/liter were applied to the seedlings until runoff using a hand pump bottle sprayer. Each field treatment was applied to four different small plots that consisted of 10 hills in 2 rows with 5 ft. between hills and 5 ft. between rows. There was 15 ft. between plots to accommodate spray equipment. Fungicide treatments were applied weekly at 120 psi from nine Teejet hollow cone D2-25 nozzles spaced 15 inches apart on a 12-ft boom sprayer. The percentages of the leaves affected by gummy stem blight were determined weekly. Weights from two harvests were combined for total yield.
In the spring of 2000, the strobilurins, Quadris and Sovran, and a plant defense activator, Actigard, were evaluated on Sangria watermelon and compared with current standards for downy mildew control, Bravo (chlorothalonil) and Dithane (mancozeb). Downy mildew developed rapidly in mid-June, with 74% of the foliage affected on June 15 in the untreated plots (Table 1). The standard fungicide treatments, Dithane + Benlate and Bravo Ultrex, were very effective in controlling the Disease. The strobilurins were not as effective against downy mildew as was Bravo, since the treatments in which they were alternated with Bravo had more disease than the bravo only treatment. Applications of Actigard in the transplant house improved the disease control in some field treatments but not in others. It was beneficial to the bravo alternated with Quadris treatment but not to the Bravo alone treatment.
In the spring of 1998, the strobilurin, Quadris, and the plant defense activator, Actigard, were compared with currently recommended fungicides for the control of powdery mildew on Sangria watermelon (Table 2) Powdery mildew appeared in the plots in late May and, by the end of the trial, control plots were nearly defoliated by powdery mildew. Quadris, was more effective on powdery mildew than the standard fungicides, Bravo and Benlate, since Quadris alternated with bravo provided the best disease control. Applications of the plant defense activator, Actigard, in the transplant house and in the field with Bravo also provided better control of powdery mildew than the currently recommended treatments.
Conclusions and Recommendations
Quadris, a strobilurin, was more effective against powdery mildew of watermelon than were the other recommended fungicides.
Current standards for the control of downy mildew of watermelon, chlorothalonil and mancozeb, were more effective than were the strobilurins.
Actigard, a plant defense activator, applied to watermelon in the transplant house and in the field contributed to the control of downy mildew and powdery mildew when combined with standard fungicides.
Transplant applications of Actigard, when labeled for use on cucurbits, could become an important tool to use in the control of downy mildew, powdery mildew, and other watermelon diseases.
When powdery mildew of watermelon occurs, the strobilurins should be utilized in the control program; whereas, with downy mildew, a standard mancozeb or chlorothalonil program is sufficient.
Table 1. Control of downy mildew and yield of watermelon, 2000.
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| Treatment (Amt/100 gal/acre) |
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| Benlate at 0.25 lb ai + Dithane at 3.0 lbs product |
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| [Actigard in transplant house] Bravo Ultrex at 2.25 lbs ai + Actigard at 0.031 lb ai |
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| Bravo Ultrex at 2.25 lbs ai |
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| [Actigard in transplant house] Bravo Ultrex at 2.25 lbs ai alternated with Quadris at 0.25 lb ai |
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| Bravo Ultrex at 2.25 lbs ai alternated with Quadris at 0.25 lb ai |
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| Bravo Ultrex at 2.25 lbs ai alternated with Sovran at 0.15 lb ai |
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| Untreated control |
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Table 2. Control of powdery mildew and yield of watermelon, 1998
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| Treatment (Amt/100 gal/acre) |
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| Quadris at 15 fl oz + Latron B-1956 at 0.6% (2) alternated with Bravo Ultrex at 2.7 lbs (1) |
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| [Actigard in transplant house] Bravo Ultrex at 2.25 lbs ai + Actigard at 0.031 lb ai |
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| Benlate at 0.5 lb + Manzate at 3.0 lbs |
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| Bravo Ultrex at 2.7 lbs |
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| Untreated control |
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Don Hopkins, Ph. D., plant pathologist
,
University of Florida
The Grower, March 2001
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Growers should also know the diseases and insects that attack each crop, and each pest’s life cycle. This sounds like a tall order, but here are some basics to get started.
Squeaky Clean
Sanitation is the first step in producing quality transplants.
Kill weeds. During the spring after transplanting or in the fall before seeding, remove all weeds from the inside of the greenhouse. Weeds serve as hiding places for thrips, mites, aphids, and whiteflies and as hosts for diseases such as tomato spotted wilt virus. If weeds are hand-pulled, immediately place in bags for disposal. Do not leave them on the floor or near the greenhouse. This is important for weeds that have flowered. If they are not removed, their seeds may spread.
If the greenhouse is kept covered over the summer, it can be solarized by wetting the floor and closing up the house. This method works best during the months of July and August, when soil temperatures can reach 1450F or higher in the greenhouse.
Another option is to find un-germinated weed seed. To do this, allow the greenhouse to dry out, remove all the visible weeds, then irrigate. The water will encourage weed germination. New weeds can then be pulled or controlled with a herbicide. Repeat the process until few, if any weeds emerge.
Building barriers. Maintain a 20 to 30 foot weed-free barrier around the greenhouse to prevent weed seed germination and entry of weed seeds through unscreened vents and doors. Use a gravel/sand mixture on top of a weed-inhibiting fabric, or gravel/sand mixture alone to suppress weeds.
Disinfect. Remove any extra mulch, flats, or equipment from the house so all surfaces can be disinfected. Trays, benches, and other surfaces should be cleaned with soapy water to remove any organic matter and debris before disinfection.
Soak used trays for 10 minutes in 10% solution of bleach per 100 gallons of solution. The pH should be maintained below 6.8 and checked every two hours for chlorine content and pH.
Once the trays have been soaked, cover them with plastic or a tarp to allow the chlorine to work. The trays should be rinsed before use. Place a few trays (while still wet) in a plastic bag for 24 hours and check for bleach odor. If the chlorine smell is present, rinse or aerate longer and check again.
Ensure Hearty Seed
The basis for acceptable yields in the field starts with a good transplant. Good transplants start with good seed. Perform a germination test a few days before planting to ensure that the germination is what the seed company has determined it to be.
Keep a seed sample from each lot in a refrigerator until the crop has been harvested to help identify the cause of problems (such as a variety not being true to type). In the greenhouse, maintain plants from the same seed lot together so if a seed-borne problem develops, the lot can be easily identified.
Other Disease Fighters
Mix preparation. When planting in trays, always use sterile mix. Use clean tools and do not dump the mix on a dirty surface. Always combine several bags of mix together before filling trays. Place trays on pallets or benches to reduce the risk of disease-causing microbes infecting the trays. If trays are to be placed directly on soil, cover the floor with plastic.
If planting directly in the soil, fumigate the greenhouse in the fall, when the soil temperature ranges from 500F to 800F.
Seed treatments. Before treating seed, determine what seed treatments have already been applied. Hot-water-treat cole crops for black rot control if it has not been done and the variety is not resistant. Treat peppers and tomatoes with a chlorine solution for bacterial leaf spot if not already treated by the seed company.
On The Alert
Scout greenhouses at least every other day, not only to identify disease, but also to evaluate problems due to water, temperature, or nutrient deficiencies or toxicities. Remove or isolate diseased plants.
Insects can be controlled to some extent by many of the sanitation practices mentioned for diseases and weeds. Additionally, screening vents will help reduce insect entrance into the greenhouse. Monitoring insects with sticky cards will help identify when a pest is present, its location, and population trends. Proper placement is the key to successful monitoring. Always place the cards right above the plant and move them upward as the plants grow. Place at least one card per 1000 square feet and change them weekly.
Irrigation Tips
Good irrigation practices are essential. Each year, obtain a water sample before seeding and have it analyzed for alkalinity, electrical conductivity, and levels of major, secondary, and micronutrients.
Check the irrigation pattern to determine if the water distribution is uniform. Place identically sized containers (tuna fish cans work well) in a grid pattern throughout the greenhouse and irrigate for a given length of time. Calculate the amount of water applied per hour for each container. From this, you can determine where too much or insufficient water is being applied.
Water early in the day to allow plant surfaces to dry out before nightfall. Check the soil at least once a day to ensure proper moisture levels. On cloudy days, the soil surface may remain wet but during sunny periods, the soil dries out quickly and may require irrigating two or three times a day. Smaller-cell trays are of particular concern. A light watering in small cells encourages roots to not grow to the bottom and fill the cell.
Fertilization Ties To Irrigation
A fertilization program and irrigation are closely linked. Excess fertilizer can lead to soluble salt injury or too much vegetative growth. Excessive irrigation can leach nutrients.
First, learn how to read a fertilizer bag to determine what type of nitrogen it contains. Nitrate is slow acting, urea is faster, and ammonium is the fastest acting. Use nitrate if the plants are not being pushed, but if more vigorous growth is needed, use ammonium. Phosphorus, urea, and ammonium can cause an acidifying effect on media, so monitor pH and electrical conductivity regularly.
Hardening Off
The most common mistake made in hardening off plants is to wait until plants are full-size before slowing growth. It is better to start when plants are half their final size. This can be done by reducing temperature 50F below the minimum growing temperature, gradually reducing irrigation, or reducing fertilization. A combination of the three is perhaps more effective.
Wesley L. Kline
Greenhouse Insider
April 2001
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While the use of integrated pest management (IPM) techniques and biorational controls has increased in the state’s number-one vegetable market over the past two years, many in the industry believe that broad-spectrum insecticides still have a vital role to play on Florida fresh-market tomatoes.
Biorational pest-management practices that are now commonly used include sprays of insect growth regulators (IGRs) and natural microbial organisms such as Bacillus thuringiensis (Bt). But are these options always effective? The stakes against pests are high—Florida produces more than 45% of all fresh-market tomatoes in the United States. Production costs are on the rise and fresh-market tomatoes must be blemish-free to maintain their market value.
The insects that impact tomato quality and yield include: southern armyworms, fall armyworms, beet armyworms, tomato fruitworms, loopers, leafminers, silverleaf whiteflies, and occasionally, stinkbugs.
Pyrthroid Pluses
Jamie Williams, farm manager for Farm Op #7 in Naples, prefers the softer products up front, but notes that “Sometimes you just need a bigger gun.” As for which gun, Williams says he prefers the newer pyrethroids to carbamates and organophosphates. “Cost-wise and in terms of worker protection, pyrethroids are much easier to work with. They don’t have the smell, and re-entry periods are shorter.”
Several manufactures of broad spectrum insecticides have improved the safety and efficacy of their existing products. For example, a next-generation pyrethroid, Warrior (Syngenta), employs a unique encapsulation process to provide extended residual control and improved handling characteristics.
Dave Schuster, research entomologist with the University of Florida in Bradenton, says that newer pyrethroids are effective at lower rates than older pyrethroids. He sees a role for them on southern armyworm larvae that may escape control by some newer insecticides.
For whiteflies, Schuster suggests an IGR as a first line of defense following an at-transplant application of imidacloprid. “If adult whiteflies are present, IGRs don’t work as well,” he says. “Then you might use a pyrethroid, a pyrethroid/organophoshate combination, or Thiodan (endosulfan, Aventis).” The combination of chemistries offers more than one avenue of attack.
Stinkbugs Strike Out
Stinkbugs pose a severe, though sporadic, threat to tomato growers. “When we were spraying pyrethroids for whiteflies, we weren’t seeing a lot of stinkbugs. But now that we’re using less broad-spectrum products in general, stinkbug populations can be a problem,” observes Phil Stansly, professor of entomology at the University of Florida. “If you look at the new materials that can be softer alternatives to pyrethroids, none of them have any activity on stinkbugs.”
Stansly notes that a mix of pests can also pose a problem for biopesticides and some of the new softer chemical products. “If you have a number of different hemipteran and lepidopteran pests, some more selective pesticides won’t cover them both. But a pyrethroid such as Warrior would be a good choice,” he says.
Charles Mellinger, general manager of Glades Crop Care in Jupiter, notes that stinkbugs can strike without warning. “You have to scout carefully and spray quickly because they feed on fruit and cause economic loss. Pyrethroids deliver a good, quick knockdown and are our product of choice for stinkbugs.”
Biopesticide Boundaries
Biopesticides are very much a rifle shot approach because they are so selective. With an eye on IPM strategies and preserving natural predators, entomologist say selectivity is generally desirable as a first line of defense. But biopesticides do have limits, and nobody knows that better than the growers who use them.
“When we’re running on a five-day schedule with no rain, we use Bts for a couple of applications. If we see any egg masses, then we use an IGR. But after the eggs hatch, you always have stragglers that make it through,” says Williams. For those situations, he has relied on a pyrethroid.
Weather-fastness is another concern. “If I’m in the fall pruning sequence, and we have bad weather and worm pressure, then I don’t hesitate to jump in with a pyrethroid. I know I’m going to get four or five days of control,” he says. “But Bts are basically uneconomical in rain showers. Bts have no staying power. They have to be on the leaf and they have to be ingested.”
“With pyrethroids, I don’t have to worry if I have to wait seven or eight days before I can go back in because of pruning, or staking and tying,” Williams adds.
Ben Stanaland of Pacific Tomato Company in Fort Myers is another farm manager who has had success, so far, with Bts. But he, too, emphasizes the importance of pyrethroids in the rotation, especially against fall armyworms.
Although Stansly would never recommend growers use pyrethroids as a calendar spray, he has used them that way experimentally as a benchmark against some newer biopesticides. In a test against southern armyworms and beet armyworms with Warrior as the grower standard, significant control was obtained with Bts. However, three times more extra-large tomatoes were harvested from plants treated with Warrior, showing that under heavy pressure Bts alone may not be enough.
“The way we like growers to use Bts in tomatoes against southern armyworms is more or less on a preventive basis. Then you have to be scouting carefully, and if you see a population getting away form you, you go in with something else,” Stansly explains.
No one wants growers to get into a firefight without the right weapon. While IPM and newer biorational controls are useful alternatives, growers draw comfort in knowing that there are big-gun pyrethroids available when needed.
Florida Grower
April 2001
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The active ingredient of Warrior is concentrated in tiny, quick-release capsules suspended in a water-based formulation. The capsules are about three microns in diameter—roughly one-thirtieth the diameter of a human hair. The insecticide is released from the capsules onto the target almost immediately after the product is sprayed.
“Warrior delivers quick knockdown of insects just like emulsifiable-concentrate formulations along with some other nice benefits of encapsulation technology,” says Steve Miller, insecticides brand manager for Sygenta. “The capsules adhere strongly to the target, improve rainfastness, and deliver UV protection which results in longer residual activity. We were able to significantly reduce formulation solvents, and there’s less potential exposure for handlers because there’s a barrier between the active ingredient and the handler.”
Florida Grower
April 2001
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“Current nitrogen prices are well below production costs," says Al Giese, Agriliance co-president. “That has forced many nitrogen producers to scale back on production or shut down plants. Nitrogen producers are struggling to survive.”
Some of the nitrogen companies that have already scaled back nitrogen production or closed production plants include Mississippi Chemical, Terra Industries Inc., Agrium, Royster Clark Inc., Potash Corp. of Saskatchewan, Koch Nitrogen Corp., Farmland Industries and CF Industries.
And the potential for more shutdowns is likely, Giese says. Without a significant warming trend this winter, natural gas prices and consequently nitrogen prices are expected to remain high, and adequate nitrogen supplies may become more difficult to obtain.
The Grower
March 2001
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The new company will develop, manufacture and market natural, environmentally responsible crop-protection and yield and quality enhancement products.
Emerald Bio has eight products registered by the Environmental Protection Agency. They include AuxiGro, NuTRx, Mycotrol, BotaniGard, Nemasys, Nemasys H, Valero and Cinnamite. The product line is based on two core technologies. The first is gamma aminobutyric acid (GABA), a naturally occurring amino acid, to increase crop yields, improve quality and combat diseases, according to a company press release.
The second is the selection, formulation and manufacture of fungal-based biological pesticides.
The Grower
March 2001
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The U.S. Environmental Protection Agency approved expanded labeling for Quadris fungicide from Syngenta. Added were more than 90 crops, including various root, bulb and leafy vegetables, and infurrow and banded applications to control soil borne diseases in potatoes.
The active ingredient, azoxystrobin, belongs to the strobilurin class of chemistry.
Quadris controls several leaf spots, rust, powdery mildew, root rot, circular spot and Rhizoctonia stem canker in sugar beets, carrots, horseradish and other root and tuber crops.
For garlic, leeks, onions and other bulb vegetables, Syngenta recommends foliar applications at a rate of 6.2 to 12.3 ounces per acre for control of purple blotch, rust and white rot. In lettuce, spinach, celery and other leafy vegetables, it controls leaf spot, mildew, anthracnose and white rust.
In addition to foliar applications, the fungicide can be used infurrow for potatoes to control silver scurf and various states of Rhizoctonia including black scurf. It already has a foliar label for potatoes to control early and late blight.
The Grower March 2001
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GENERAL RECOMMENDATION
The key to successful broadcast treatments with Roundup brand herbicides is the use of low carrier volumes, and the key to a successful chemical fallow program is the timing of the applications. Two Roundup UltraMAX treatments with one tillage trip in between should be utilized during the entire fallow period.
FOLLOW THESE RECONIMENDED STEPS:
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A little old couple walked slowly into McDonald’s one cold winter. They looked out of place amid the young families and young couples eating there that night. Some of the customers looked admiringly at them. You could tell what the admirers were thinking; “Look, there is a couple who has been through a lot together, probably for 60 years or more!”
The little old man walked right up to the cash register, placed his order with no hesitation, and then paid for their meal. The couple took a table near the back wall and started taking food off the tray. There was one hamburger, one order of French fries, and one drink. The little old man unwrapped the plain hamburger and carefully cut it in half. He placed one half in front of his wife. Then he carefully counted out the french fries, divided them in two piles, and neatly place one pile in front of his wife. He took a sip of the drink, his wife took a sip and then set the cup down between them.
As the man began to eat his few bites of hamburger the crowd began to get restless. Again you could tell what they were thinking: “That poor old couple. All they can afford is one meal for the two of them.” As the man began to eat his french fries one young man stood and came over to the old couple’s table. He politely offered to buy another meal for the old couple to eat.
The old man replied that they were just fine. They were used to sharing everything. Then the crowd noticed that the little old lady hadn’t eaten a bite. She just sat there watching her husband eat and occasionally taking turns sipping the drink. Again, the young man came over and begged them to let him buy them something to eat. This time the lady explained that no, they were used to sharing everything together.
As the little old man finished eating and was wiping his face neatly with a napkin, the young man could stand it no longer. Again, he came over to their table and offered to buy some food. After being politely refused again he finally asked a question of the little old lady. “Ma’am, why aren’t you eating. You said that you share everything. What is it you are waiting for?” She answered…”The teeth.”
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Over the past two years, the Agricultural Research service geneticist, colleagues at the ARS U.S. Vegetable Laboratory in Charleston, S.C., and researchers at North Carolina State and Clemson Universities screened watermelons to find those that are disease and pest resistant.
Fusarium wilt and gummy stem blight are the most destructive watermelon diseases. The researchers are evaluating plant introduction accessions stored at the U.S. Department of Agriculture Germplasm Collection center in Griffin, Ga. They have also checked the cultivars for resistance to silverleaf whiteflies that infest watermelon fields, damage the crop and introduce plant viruses.
The value of the U.S. watermelon crop in 1999 was more than $268 million. In some wet years, Fusarium and gummy stem blight can cause up to 15% yield loss to this high-value fruit.
The team’s goal is to evaluate the genetic diversity of watermelon germplasm and to develop watermelons with enhanced disease and pest resistance. The scientists are constructing a genetic linkage map of watermelon genes. The map will be useful in breeding programs, locating genes that confer disease resistance and genes that affect fruit qualities like fruit shape and size, flesh color and sugar content.
Watermelon are grown on 2% of the world area devoted to the production of vegetables. Although many watermelon varieties have been developed worldwide during the past two centuries, there is still an ongoing need to improve watermelon fruit qualities and better meet market demands.
So far, the team has found wild watermelon accessions that are resistant to whiteflies but not to gummy stem blight. The scientist are continuing to screen the plants for resistance to Fusarium and gummy stem blight diseases.
The Grower/March 2001
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YOU ARE HIRED!
Back in the time of Samurai there was a powerful emperor who needed a new head Samurai, so he sent out a declaration throughout the country he was searching for one.
A year passed, and only 3 people showed up: a Japanese Samurai, a Chinese Samurai and a Jewish Samurai.
The emperor asked the Japanese Samurai to come in and demonstrate why he should be head Samurai. The Japanese Samurai opened a match box, and out popped a bumblebee. Whoosh! went his sword, and the bumblebee dropped dead on the ground in 2 pieces. The emperor exclaimed: “That is impressive!”
The emperor then asked the Chinese Samurai to come in and demonstrate his skills. The Chinese Samurai also opened a match box, and out buzzed a fly. Whoosh, Whoosh! went his sword, and the fly dropped dead on the ground in 4 small pieces. The emperor exclaimed: “That is really VERY impressive!”
The emperor then had the Jewish Samurai demonstrate why he should be the head Samurai. The Jewish Samurai also opened a match box and out flew a gnat. His flashing sword went Whooooosh! Whooooosh! But the gnat was still alive and flying around.
The emperor, obviously disappointed, asked: “After all of that, why is the gnat not dead?”
The Jewish Samurai smiled. “Well,” he replied, “circumcision is not meant to kill.”
Freda, an eighty-three year old lady finished her annual physical examination whereupon the doctor said “You are in fine shape for your age.. but tell me.. do you still have intercourse?” Just a minute.. I’ll have to ask my husband,” she said. She went out to the reception room and said: “Jake do we still have intercourse?” Jake answered impatiently…..”If I told you once I told you a thousand times...We have Blue Cross!!”
