REPORTS FROM THE FIELD (as of July 26)
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)
TARNISHED PLANT BUG
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.
TPB/MYCOTROL UPDATE (from Paul Sachs)
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.
TPB PARASITE UPDATE
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...
FARMER GROWER GRANTS
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 nesare@zoo.uvm.edu