Cooperative Extension Service 
________________________________________________
Institute of Food and Agricultural Sciences
 

Hendry County Extension P. O. Box 68 LaBelle, Florida 33975-0068 Phone (941) 674-4092

SOUTHWEST FLORIDA
VEGETABLE PEST AND DISEASE
HOTLINE

February 18, 1999

A weak cold front pushed through the area on the weekend of February 13 -14.  This front bought generally drier air and dropped average temperatures from daytime highs in the low 80's and nighttime lows in the mid 60's to a more seasonable range from the mid to upper 70's days and low 60's to upper 50's at night. Light rain fell in the early morning hours of February 18.  Accumulations ranged from .10 of an inch in east Naples and eastern Charlotte County to an inch and a half in the Devil's Garden area. Naples reported .90 inch and the FAWN weather station at Immokalee recorded precipitation of .35 inches. The morning fogs that have plagued the area the past few weeks have abated somewhat although morning dews remain heavy.

Late blight has been identified on tomato in at least one location around Immokalee.  This diagnosis has been confirmed by lab analysis and is most likely the US 17 strain.  Research conducted at the University of Florida indicates that late blight may move from potato to tomato and vice versa.  Under temperature and moisture conditions conducive to the development of the disease (which exists throughout most of our growing season), growers are advised to apply protective fungicides before infections are identified in the field.

Late blight remains widely present on potato around the region. Infection levels are low to moderate. Reports indicate that the disease appears to be under control in most fields with some patchy outbreaks of new disease activity being noted in few locations.  See comments above.

Gummy stem blight is being reported from widely scattered locations on watermelon and cucumber.  Infection levels are generally low.  Some growers have reported a flair-up of this disease on advanced plantings about 10 -14 days ago but improved weather conditions and judicious control programs have gotten the situation under control.  A few isolated cases of target spot have also been noted on cucurbits.

Downy mildew is also present on cucurbits and has been identified in at least two locations on cantaloupe, squash and watermelons.  Infection levels are low with the exception of older squash plantings that have been picked several times where both downy mildew and powdery mildew are present at moderate levels.

Armyworm activity continues to be noted by respondents from locations across the region.  Sightings include beet, and southern armyworm depending on the location. Numbers and crop damage has been low

Extremely high whitefly populations are being reported all across the region on cucurbits, beans, potatoes, and tomatoes. Many respondents are reporting the influx of high numbers of whiteflies coming in on new plantings as nearby fields are destroyed.  In addition to the use of imidicloprid in the plant house and at transplant many growers are resorting to thiodan and pyrethroid/organo-phosphate sprays to knock down high populations of adults.  Some growers have used soaps and oils with good results. Use of some of the new insect growth regulators (IGR's) to combat whiteflies should also be considered. Knack is a juvenile hormone analogue that sterilizes eggs, either in the female or after they have been laid.  It has no effect on the nymphs until they pupate. No adults will emerge from treated nymphs.  Applaud kills at any molt.  These materials should be used to control whitefly after the effects of Admire have worn off.  To avoid the buildup of resistance no more than two applications of either material should be applied during the season and should be alternated rather than applied consecutively. Additional recommendations include rigorous summer clean-up and crop destruction with whitefly control.

TYLCV is widely present across the area. In general, the incidence of infection is low (less than 1%) and confined to a few plants per field, although a few isolated fields showing between 1 - 5% infection. At present most of the spread appears to be from other infected plants rather than transplants. Affected plants should be rogued-out upon identification. After the first tie, growers are reporting good results with spot treating infected plants with an insecticide to kill infected whiteflies and cutting the plants off at soil level and leaving them in place.  Growers are urged to maintain their vigilance in combating this disease and it's whitefly vector to avoid the buildup of TYLCV to levels being observed in other areas of the state.  For more information on TYLCV and whitefly management contact the Hendry County Extension Office.

A few scattered reports of broad mite on pepper have been received. Incidence in any given field is spotty.  Depending on conditions, populations may begin to build as warmer drier weather returns to the area.

Bacterial spot activity is relatively low.   Incidence is sporadic and infection levels are generally light. A few isolated reports of low levels of early blight infection on tomato are being noted.

Thrips counts continue to increase.  These are primarily common flower thrips (F. bispinosa), although melon thrips (T. palmae) are reportedly predominate in some areas. Use of pyrethroids for other pests can cause T. palmi populations to increase dramatically. T. palmi are normally on the leaves, which is one way to distinguish them.  The SWFREC diagnostics lab can identify insects and disease for growers. Damage reports remain low.

Sporadic, low levels of aphids have been observed in a number of areas on brassicas, cucurbits, pepper, and potato.  Programs to control other pests seem to be keeping these in check.

Pinworms are being caught in traps in scattered locations across the area.  In some cases counts from traps have reached 45 moths per night.  There have been only a few scattered reports of pinworms or eggs being found on plants.  A few pickleworms have been identified on cucumber in one location.

Pepper weevils are beginning to be reported widely across the area particularly in older plantings and specialty peppers, although they have also been noted in some young fields as well.  Damage has been low in most instances.  Traps have indicated an increase in overall populations.

Leaf miners are widely present throughout the area. Populations appear to be stable or decreasing from most reports.  Most respondents indicate leaf miners are currently under control.

There have been reports of an increase in root-knot nematode problems, even where methyl bromide has been used.  Problems seem to be associated with fields having a history of long and continued cultivation of the same crop.  In these cases, nematode populations become so high that there are sufficient numbers at depths below the reach of the fumigant. Growers should practice crop rotation and consider the use non-susceptible cover crops during the off season.  Addition of organic matter may help to provide a healthy environment for plant growth and improve the efficiency of drip irrigation and injected nematode suppressants like Vydate.

Contributors include: Skeeter Bethea/Joiner Farms, Kathy Carbeiner/Severts Farm, Jim Cornellie/Tri-Campbell, David Harloff/Pacific Tomato Growers, Fred Heald/Farmers Supply, Sarah Hornsby/AgriCropCon, Leon Lucas/Glades Crop Care, Gene McAvoy/Hendry County Extension, Alice McGhee/Thomas Produce, Chuck Obern/C+B Farm, Doug Purvis/Terra, Wade Purvis/Silver Strand, Dr. Pam Roberts/SWFREC, Wes Roan/6 Lís, Jay Shiveler/F+F 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.

Special Thanks to the generous support of our sponsors; who make this publication possible.
 

Gene McAvoy
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                                     gmcavoy@ifas.ufl.edu

The Institute of Food and Agricultural Sciences is an Equal Employment Opportunity - Affirmative Action Employer authorized to provide research, educational
information and other services only to individuals and institutions that function without regard to race, color, sex, age, handicap or national origin.
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

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