Welcome to the University of Connecticut Cooperative Extension System=s Vegetable Pest Message. 
This message is being recorded on Friday afternoon June 19 by Jude Boucher.   

This week's message will cover:

• European corn borer

• Setting up your corn earworm traps

• Critical time to scout for early blight on tomatoes

• Powdery mildew on early summer squash plantings

• Potato leaf hoppers starting

• Potato pests in low-spray situations

• Hazardous waste collection

European corn borer (ECB)
We captured 2 ECB moths in pheromone traps in Berlin and 7 in Shelton this week.  The Shelton site was up slightly from last week while the Berlin site stayed low.  The highest infestation I found in the western portion of the state this week was 2% of the plants with larvae.  I didn=t get a chance to scout any corn in the mid-whorl to pre-tassel stage in the valley, where things might be slightly ahead of the western hills.

Keep scouting mid-whorl through pre-tassel stage corn this coming  week.  Look for small shot-holes in the youngest leaves in the center of the whorl or for tiny newly-hatched larvae or their frass or manure between the fingers of the pretassel plants.  Check 50 plants per block in groups of 10 plants at a time.  Spray pre-tassel stage fields that have more than 15% of the plants infested.

Here is a list of infestations found at different sites while scouting sweet corn this past week. *means that the planting is over threshold and should be sprayed.  MW=mid-whorl, LW= late-whorl, PT=pre-tassel, S=silk.

Town	% infested plants	Stage of planting	ECB moths trapped	CEW moths/N
Shelton	2%	LW-PT	7 moths
Berlin		PT	2 moths	0 = no spray

Set up your corn earworm traps
Before your first sweet corn fields begin to silk, you should be setting up your corn earworm (CEW) pheromone traps.  Remember your pheromone traps are your eyes in your corn field when you are not there.  Use one or two Scentry Heliothis traps baited with a Hercon brand lure and place the traps in fresh silking corn fields.  Change the lures every three weeks and keep the extra lures in a zip-locked bag in the freezer until you need them. I=ll give you the CEW action thresholds next week.  The only trap that was up and checked this past week was in Berlin which failed to capture any CEW moths.  No CEW sprays were required in Berlin this past week. 

Critical time to scout for early blight on tomatoes
People are asking me if they should put a preventative fungicide spray on their tomatoes due to the extended period of wet weather.  One grower down in Gales Ferry, who already has a weather station for apple disease predictions, is using the TomCast disease forecasting model to predict when his first spray should go on for early blight. Last year the model predicted the first spray should be applied on the same day we picked up early blight lesions in our field scouting at that farm. The model is based on leaf wetness and temperature.  Basically, the further the temperature is from the optimum of 74 degrees when the leaves are wet, then the slower the disease severity units accumulate.  Because the temperatures have been so cool lately, we have not accumulated as many DSU as one might think and we have not reached the threshold of 35 DSU=s required for the first application.  However, the weather forecast is calling for more showers through next Thursday and rising temperatures.  So we expect the model to predict the first early blight spray early next week.  After that the model calls for repeat sprays every 15 DSU=s.

Growers who do not have a weather station and computer models, can scout for early blight on a weekly basis by looking for yellow leaves at the bottom of the plant that have small circular spots with concentric rings like a target.  As soon a you find the fist early blight lesion, you should begin fungicide applications on a 7-14 day schedule.  Generally, make an application about every 10 days, but tighten the schedule during prolonged periods of wet weather, and loosen it slightly if the weather is consistently dry.  If you have any left over maneb or Manzate, you can use this for early blight on tomatoes prior to fruit turning pink.  Other options once harvest begins include fungicides such as Cabrio or Bravo.  See the New England Vegetable Management Guide for addition options.  If you are making a late planting of tomatoes, remember to locate it upwind and as far from the first planting as is possible so that it doesn=t get bathed in early blight spores from the first planting.

Another thing to consider is spray coverage.  Obviously, trellised and pruned plants allow for better air circulation and faster drying time than ground tomatoes.  You can also improve your spray coverage by trellising, but not if you are trying to spray multiple rows with a mist blower or airblast sprayer.  When using an airblast sprayer on trellised tomatoes, the first row(s) prevents the sprayer from providing good coverage to the lower portion of the inner rows. Since early blight starts on the lower leaves, these unsprayed lower portions act as a spore factory that bath the plants in new spores all the time, which eventually results in the failure of your fungicide program.  Consider constructing a system where you can either spray between each row for better coverage, or use a boom sprayer with drop nozzels to deliver the material where it is needed the most. 

Powdery mildew on early summer squash plantings
I found powdery mildew on an early summer squash planting this week in Suffield.  Some growers simply plant enough summer squash to withstand the losses that this disease causes. However, if you choose to spray to control powdery mildew you can use Pristine, Procure or sulfur on a 10 day schedule.  If you choose to use sulfur, the brand Microthiol Dispress mixes very well and is inexpensive.  

Potato leaf hoppers
Low levels of adult leafhoppers are now present on beans and potatoes. We haven=t seen high levels on any farm so far this year, but we expect them to arrive from the south any time now.  Feeding can severely damage potato and bean plants and higher levels can damage eggplants. The insects feeding is toxic to the plants and causes symptoms known as hopperburn. Hopperburn starts when the tip of the leaf turns yellow, and  is usually followed by much more extensive leaf burning. You should be watching your beans and potatoes for leafhopper infestations.  Adults are small, pale-green, wedge-shaped insects that usually feed on the underside of the leaves, and can be seen streaking away from the plants as foliage is disturbed.  If you have trouble seeing these insects you can monitor with a sweep net. Later on, bright-green nymphs will be produced and can be monitored by visually inspecting the underside of the lowest leaves.  Treat potatoes if more than 1 adult leafhopper or 15 nymphs are found on 50 compound leaves.  Seedling beans should be treated if you find more than 2 PLH per foot of row.  Between the third leaf and bud stage, treat beans if you find 5 PLH per foot of row. Do not treat beans once they begin to bloom.  On small bean plantings, leafhoppers can be controlled until bloom with row covers, which will prevent yield losses.  Remove the row covers after the bud stage and before bloom.  Treat eggplant if more than 1 or 1.5 leafhoppers are found per leaf.  

Potato pests in low-spray situations
On two farms that do not spray their potatoes we found a couple of pests that you don=t tend to see on farms where insecticides are used.  The first was the three-lined potato beetle.  This is a smaller relative of the Colorado potato beetle, which resembles a large, fat cucumber beetle.  Before the CPB extended its range to the East Coast and the use of insecticides became common, the three-lined potato beetle was far more common. Now it mainly shows up on organic farms and can cause substantial damage if allowed to accumulate in large numbers.  The second oddity we found this week was the tortoise beetle.  This insect resembles a ladybug with flattened edges, but it too is a leaf feeder and a closer relative of the CPB than a true lady bug.  The flattened and spined larvae have the odd habit of holding on to its cast skins and fecal matter to use as a shield against predators, in other words, they carry it around on their backs.  This insect can occasionally be found feeding on tomatoes or potatoes in low-spray or no-spray situations.  There is also a closely related species, the golden tortoise beetle, which is more common and destructive on sweet potatoes.  Both the three-lined potato beetle and the tortoise beetle can be easily controlled with foliar insecticides, such as SpinTor or Entrust, but they rarely cause enough damage to potatoes or tomatoes to warrant treatment. 

Three-lined Potato Beetle photo:  Whitney Cranshaw, Colorado State University, Bugwood.org click image for a larger view

Tortoise Beetle photo: Whitney Cranshaw, Colorado State University, Bugwood.org click image for a larger view

Hazardous waste collection
Years ago Connecticut Department of Environmental Protection (DEP) use to sponsor pesticide collections for commercial pesticides that were no longer labeled.  This allowed growers to clean out some of the older products from their pesticide storage sheds without bearing the full cost of disposing of these hazardous wastes. In recent years, one grower has been bringing his old pesticides to the local Household Hazardous Waste Collection in his town.  We checked with DEP to see if this was permitted, because I know the Hazardous Waste Collection in my town does not permit products from commercial operations.  DEP said that they do not plan to run any commercial disposal days and that growers should be able to get rid of old products at household hazardous waste pickup days.  These local collection sites are now permitted to take such products, but some do not choose to, so it is best to call in advance to see if your products will be accepted.  There may still be a fee involved for disposal, but it will certainly be less than if you tried to contract with a hauler yourselves.  To find out when the next collection will occur in your town, go to the DEP web site at www.ct.gov/dep/site/default.asp, then click on Material & Waste Management, and then the Household Hazardous Waste in the Quick Links.  Next click on Household Hazardous Waste Collection Schedule.  Contact information, such as telephone numbers are provided so that you can call ahead.