Institute of Food and Agricultural Sciences
Hendry County Extension P. O. Box 68 LaBelle, Florida 33975-0068 Phone (941) 674-4092
VEGETABLE PEST AND DISEASE
April 29, 1999
Although some rain has been received across the area of the past two weeks and particularly the past few days it is too late to alleviate the effects of the drought that has affected southwest Florida over the past few months. Although welcome, it is unfortunately too late to mitigate the drought-related problems, experienced in many crops. In fact, torrential showers in some areas may cause growers additional problems with increased disease pressure and physical damage to standing crops.
A cold front moved through the area on April 17th, which dropped temperatures into the 40s and produced a steady light rain for several hours that produced very little total precipitation in most areas. The FAWN Weather Station at Immokalee reported 0.15 inches of rainfall from this event, while other respondents reported between 0.10 and 0.50 inches of precipitation.
The past few days have seen a significant rainfall in some areas, with a typical summertime rainfall pattern establishing itself. In the Devils Garden area, some growers have reported over 4 inches of precipitation since Monday, April 26. On May 28, some areas north of LaBelle received upwards of three inches of rain and some hail was reported. Showers have been localized and most areas are reporting far less total accumulation. The FAWN Weather Station has recorded a combined total of only 0.60 inches of precipitation for several rain showers, which fell from April 26-28. Forecasters are predicting a 40 50% chance of rain over the next few days. It is too early to tell whether or not this signals the beginning of the rainy season and relief from the long running drought. Day time temperatures have ranged from the high 80s to the low 90s, while nights have fluctuated from to the mid 50s to the mid 60s.
Despite the rain, most growers continue to report difficulty in maintaining adequate soil moisture levels for optimum crop growth. Drought induced moisture stress has manifest itself in terms of reduced yields, smaller fruit size and compromised fruit quality. Tomato ripening has been greatly accelerated by the heat and drought and the spring crop promises to be a short one. Sunscald is causing concern to pepper and melon growers. Additional drought-related problems, which are being reported, include salt injury to crops in some isolated cases, blotchy ripening, and a widespread increase in the level of blossom end rot on tomatoes and other crops.
The pest and disease situation has remained relatively static over the past two weeks. Since most crops are nearing completion, growers have scaled back control programs and are only applying chemicals were and when needed to bring in the crop.
Melon thrips (Thrips palmi) have built up rapidly in number of locations around Immokalee and are causing concern on a number of crops, particularly cantaloupe and watermelon. Populations appear to be building up over a succession of vegetable crops that includes just about everything but tomato. A typical scenario starts with potato, where thrips build up and then move to melons when the potato vines are desiccated. Numbers then rise to high levels across successive melon plantings. Beans are also prime candidates for growing and releasing large numbers of thrips. A good strategy would be for growers not only to destroy infested crops in a timely manner but also to kill as many thrips as possible. Application of a tank mix, of something like Lannate plus Guthion, at the highest labeled rates and plenty of water followed by thorough disking should help minimize possible movement from older plantings to younger crops.
Flower thrips (F. bispinosa) are widely present and appear to be increasing somewhat in certain locations on pepper and tomato, while declining or stabilizing in others.
Armyworms are widely present across the area. A number of growers are reporting significant numbers of beet armyworm and southern armyworm in cantaloupe, pepper, tomato and watermelon.
Pinworms are widely present and increasing on tomato. Pheromones appear to be working for the most part although some respondents are reporting that they have had to resort to harsh chemicals in order to obtain control. There have been no reports of fruit damage.
Several reports of pickleworms have been received from widely scattered sites. Several reports of rind worm damage on melons attributed mostly to beet and southern armyworms and cabbage loopers - have been noted. Crop damage has been minor for the most part and several growers are reporting significant control as a result of efforts to combat melon thrips. Spray coverage is critical to prevent rind worm damage.
Extremely high whitefly counts are being reported from a number of locations and seem to be on the increase, particularly in cantaloupe, tomatoes and watermelons. In some older tomato and watermelon plantings whitefly numbers have reached sufficient levels to cause sticky fruit.
Diamond back moths continue to be seen sporadically in brassicas.
Pepper weevils continue to build across the area particularly in older fields. Some respondents indicate that despite the continued presence of weevils, they are largely under control.
Downy mildew has cranked up in several widely scattered locations across the area. Growers are reporting increased incidence of the disease in cantaloupe, squash, watermelon and specialty melons. Prediction of continued rainy weather over the next few days may create ideal conditions for the rapid spread of this disease and growers are advised to take protective measures.
Powdery mildew is present on older plantings of squash and is being seen on tomato and pepper in isolated cases.
Mosaic is widespread on melons across the region. Some fields have reached moderate to high infection levels. In some older fields, plants that were infected early are yellowing, wilting, and ultimately dying. In some instances, wilted leaves are burning on hot sunny afternoons and then present symptoms which mimic downy mildew.
Gummy stem blight is widely present on watermelon through out the area. Incidence is mostly low to moderate.
Fusarium wilt continues to be reported widely on watermelon. In most instances, only scattered plants are being affected in any particular field, although there have been some isolated cases where losses have been moderate to high.
There has been one isolated report of southern blight affecting tomatoes. The problem has coincided with warming soil temperatures.
Growers continue to combat spider mites on tomatoes and cucurbits in several locations. A number of growers are reporting the highest levels in several years.
Broad mites continue to increase and some fields are reaching low to moderate levels of infestation.
Cucumber beetles are being reported on a number of crops and are of concern on leafy vegetables to damage to foliage and subsequent loss of quality.
Tomato yellow leaf curl virus is widely present on tomato across the region but levels appear to have stabilized in the 2- 5% in most cases. Field sanitation is one of the most important tactics in vegetable pest and disease management. Remember back only a few years ago, that only by universal cooperation among growers were we able to survive the whitefly and Gemini-virus situation. The best thing that growers can do for themselves and their neighbors is to clean up crop residues promptly after harvest.
Calendar of Up-Coming Events:
May 6, 1999 Vegetable Field Day SWFREC - 10 AM to Noon focus on Spring Research Trials
May 12, 1999 Vegetable Meeting SWFREC 6 PM to 8:30 PM Methyl Bromide Alternatives Fumigants
May 13, 1999 FACTS Sprayer Field Day SWFREC 10 AM to 3 PM Sprayer calibration, demonstrations and more.
Contact the Hendry County Extension for more information.
May 13, 1999 Sakata
Seed Southeastern Vegetable Field Day SR. 82, Lehigh Acres 10 AM
Call 941-369-0032 for reservations and information
Contributors include: Earl Bone/Pero, Kathy Carbiener/Severts, Fred Heald/Farmers Supply, Leon Lucas/Glades Crop Care, Gene McAvoy/Hendry County Extension, Alice McGhee/Thomas Produce, Chuck Obern/C+B Farm, Wade Purvis/Silver Strand, Dr. Pam Roberts/SWFREC, Wes Roan/6 Ls, Kevin Seitzinger/Gargulio, Jay Shivler, F& F Farm, Mike Stanford/MED Farm, Dr. Phil Stansly/SWFREC, and Dr. Charlie Vavrina/SWFREC.
The SW Florida Pest and Disease Hotline is compiled by Gene McAvoy and is issued on a biweekly basis by the Hendry County Cooperative Extension Office as a service to the vegetable industry.
Extension Agent II
Vegetable/Ornamental Horticulture 941-674-4092 phone
Hendry County Extension Office 941-860-8811 mobile
PO Box 68 941-674-4097 fax
LaBelle, FL 33975 email@example.com
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COOPERATIVE EXTENSION WORK IN AGRICULTURE, FAMILY AND CONSUMER SCIENCES, SEA GRANT AND 4-H YOUTH, STATE OF FLORIDA, IFAS, UNIVERSITY OF FLORIDA, U.S. DEPARTMENT OF AGRICULTURE, AND BOARDS OF COUNTY COMMISSIONERS COOPERATING