August 1, 1999
Compiled by Vern Grubinger, University of Vermont Extension
(802) 257-7967

Still very dry, but we're managing to keep up on the irrigation, so crops look OK. Following TOM?CAST calculations I had a long interval (14 days) between tomato sprays in mid-July due to the dry weather, but the weekend of July 24 was wet and warm which is real blight weather, so I shortened up to 7 days. I got caught off guard by cabbage worms in early July, as usual, but I have them under control now. They normally aren't too bad in July and then need weekly attention in August. My potatoes have always gone down early, with yellow lower leaves and curled margins, and I had assumed it was early blight, like in the tomatoes. It turns out it was potato leaf hopper. I sprayed twice for them and the crop looks fantastic. Lesson learned: Know your pests! (Starksboro)

Getting some long overdue rain here, finally. Driest May and June ever according the old farmers around here. Our IPM scout had us spray for European corn borer in the sweet corn. Leaf hoppers are on everything from germinating beans to beet greens as well as new plantings of strawberries. Peppers are just starting to flower, we are watching out for a TPB problem there. Picked our first melons July 20 and all 8 varieties of potatoes are available the stand. Sales holding up well except when it gets really hot and humid and then they crash. (E. Hartland)

Now that I know what Galinsoga looks like (thanks to the great IPM workshop at Lewis Creek Farm), I see it flowering everywhere. Yuck. And tarnished plant bugs are on everything (except the Galinsoga).

Early sweet corn came in last week with good flavor, customers pleased despite many under-developed tips and small ears. Next sweet corn in succession (72 day) just ready, very large 9 inch ears with nice fill and knockout flavor. Bush beans winding down. Many green tomatoes. Cucumber beetles licked for now. A neighbor has Japanese beetles on his sweet corn, as many as 20 on each ear and they are devouring the tips! We have never seen any on our corn but are worried they might migrate over to our fields. (Charlotte)

What's the plus side of growing in a dry year? No corn earworm, no foliar diseases, no wet sneakers in the morning. Crops doing well thanks to drip tape and spot showers. Nice garlic crop harvested, good melon set, and, corn picking great on heavier soils. Growing conditions in the hot weather are so good we're wondering what will be left after labor day. Greenhouse tomatoes suffering from high temps, everyone seems to be out of fruit at the same time again. There's a fortune awaiting the grower who can produce a consistent crop of tomatoes through the summer. Thrips a problem on onions, cabbage moths fluttering between Bt sprays, and leafhopper and tarnished plant bug everywhere but the fort is still holding. Fall flowers sizing up and almost ready to sustain continued good garden center sales into autumn. Still, a rainy day would be nice. (Dummerston)

Hot dry conditions with no relief in sight. We continue to irrigate both for moisture and to improve lettuce seed germination and pepper blossom set. We recently discovered that it's not a good idea to irrigate over row covers on a hot day. It's not something that we have ever had a problem with but some of the greens just melted away, others look very stunted. Disease and pest pressure remain low, with the exception of flea beetles. (Hadley MA)

This is the year of the TPB! I'm getting many calls from growers with huge numbers of this native pest in their crops. I have seen whole plantings of lettuce destroyed by TPB feeding on midribs inside the heads, followed by secondary decay organisms. Beans, beet, broccoli, potato, small fruits and tree fruits can all be attacked - more than 50 crops of economic value are targets. The adult TPB is about 1/4 inch long, flat, and brownish with irregular white, yellow and black markings. The nymphs are yellowish green. Both have piercing-sucking mouthparts and inject a toxic saliva into the plant when feeding. Besides the well-known catfacing of strawberries, TPB causes leaves to be deformed, stems or petioles to become discolored, and flower buds to be deformed or fall off. Adults and probably nymphs overwinter in protected places such as leaf litter and tree bark. In the spring adults lay eggs in the stems, petioles or flower florets of herbaceous weeds and vegetables. In about 10 days the nymphs emerge, feeds on sap, grow rapidly and molt 5 times, becoming adult in about a month, so several generations can occur each season. Because the adults are very mobile, insecticides provide only temporary control. Row covers applied to clean ground immediately after setting or sowing plants may offer some protection. Good weed control and maintenance of short grass turf around fields might limit population build up. Mowing of established weeds areas or leguminous hay can drive TPB into adjacent crops. A couple of growers report that a trap crop can limit TPB damage: red clover or marsh-mallow may be worth a try.

Many folks have called North Country Organics looking for Mycotrol, a biological insecticide containing Beauveria bassiana (Bb) to control TPB, tarnished plant bug (Lygus lineolaris). We appreciate the opportunity to serve and to explore new products but our research on Mycotrol turned up the following: Tech support at Mycotech Corporation told us that efficacy controlling Lygus with Bb was inconsistent at best. They no longer list the tarnished plant bug on the label of Mycotrol or Botanigard (another of their products that contains Bb). Apparently, Bb cannot live on the top surface of the plant leaves for very long, especially in hot weather. Bb are most effective at controlling insects that frequent the underside of the leaves because the micro environment there is much more moist and cool. Unfortunately, the tops of the leaves are where the Lygus reside. Although it is somewhat of a moot point, Mycotech is planning a version of Mycotrol that contains a vegetable oil base instead of petroleum for certified organic growers but it isn't available yet. The only organic product we've found thus far that is labeled for controlling the tarnished plant bug is rotenone 5% but we'll keep looking.

Perestenus digoneutis is a wasp from northern Europe that lays its eggs in tarnished plant bug nymphs. It is expensive to rear, and is not commercially available. First released in the mid-Atlantic states in 1979 by Dr. Bill Day of the USDA Beneficial Insects Research Lab, over the next decade the parasite increased in numbers and moved northward. Eventually, it caused 40 to 50% parasitism of TPB in alfalfa fields in northern New Jersey and adjacent New York resulting in a 75% reduction in TPB population. In 1995-96, it was found in southern NH and VT alfalfa fields. According to Dr. Day, it is likely to have spread further north since then. Another parasitic wasp which attacks TPB eggs is called Anaphes iole. This is commercially available, but Dr. Day is skeptical of its effectiveness in the field, since it is short lived and inundative releases would be rather expensive. The best hope for biocontrol appears to be habitat modification that encourages the establishment of P. digoneutis while limiting TPB buildup - perhaps strips of unmowed alfalfa near vulnerable crops? More research is needed...

The Northeast Sustainable Agriculture Research and Education program (SARE) offers funding for farmers to try a new crop, an innovative marketing or production technique, or a practice that will be beneficial to your community. In 1998, the average grant size was $3300. Application forms are now available funding in 2000. These must be mailed by Dec. 6, 1999. Contact: NE SARE, Hills Building, Burlington VT 05405-0082 or call (802)656-4656 or E-mail