July 1, 1999
Compiled by Vern Grubinger, University of Vermont Extension
(802) 257-7967 verng@sover.net

Diamondback moth larvae found in Grand Isle, Fairfax, Colchester, Hinesburg, and Shoreham. Most brassicas can withstand heavy feeding until heading. Imported cabbageworm larvae seen in Colchester and Fairfax. These tend to cause more damage than diamondback, and should be monitored carefully. Potato leafhopper is widespread, and should also be closely monitored as populations can increase greatly in a short period of time. Some varieties of a crop are much more susceptible than others to hopper damage. Onion thrips found in Shoreham in large numbers, these can reproduce quickly in dry weather. Aphids found in Brandon on tomatoes and peppers. There are many natural enemies of aphids, so they are usually not a problem outdoors. In a hoophouse in Fairfax, two-spotted spider mites found. Check leaves carefully for mites in greenhouses, along with aphids. European corn borer larvae feeding sweet corn leaves in Fairfax and Colchester. Phomopsis identified in Charlotte. This disease infects blueberries, causing tip dieback while oval cankers form on the lower part of the stem, which are breeding areas for the fungus. Cane Borer found in raspberries in Hinesburg. To minimize insect and disease pressure remove the dead canes as soon as possible in brambles and blueberries. Some damage from tarnished plant bug in lettuce at Colchester, and this pest is affecting many other crops. (Pam Adams, IPM Scout)

We've had fairly dry weather with just enough passing thunderstorms to keep us going. As a result my Tom?cast calculations for tomato early blight have not called for a spray yet. It looks like I'll do my first spray sometime the first week in July. I'm right in the thick of Colorado potato beetle (CPB). I've been spraying once a week with Bt and we're about neck and neck. With Bt you have to catch the larvae when they're still small. This is the whole trick, and if you wait until there is significant defoliation you're lost. We had some PLH sighted June 16 but levels were low and no nymphs were seen. By June 23 I reached the threshold and sprayed. The threshold for leafhopper on potato is 10 nymphs per 100 mid?plant leaves. I'm keeping an eye out for cabbage worms any time soon. (Starksboro)

Few cuke beetles in the squash blossoms and not enough to spray yet. Despite a mediocre berry crop, it remains Botrytis and slug-free and our u?pickers seem to be turning out in force. Bedding and greenhouse plant sales strong through June and farmstand sales strong as well as well. Picked off our first planting of peas (started June 18) and have started with summer squashes. Field cukes should be in this week, melons are hardball size. The lack of rain has the help discouraged as well. Many good ag practices are abandoned when all your hours are spent moving irrigation pipe around. (E. Hartland)

We are even watering winter squash and corn which we have never done before. Crops are looking great for the most part, with very little insect or disease problems. Weeds have been very easy to kill. Fields are looking very clean we have been pre-irrigating fields in order to seed and have had excellent germination. Spent the week seeding fall roots and brassicas. Strawberries and peas have been excellent in flavor and will be done soon. Summer squash and beets are coming in strong with carrots and beans not far off. (Hadley MA)

Not one cucumber beetle to report on this year! Loads of CPBs but we sent them packing with two applications of Bt. Really dry. Diamondback and importedcabbageworm larvae around. Corn borer damage in first corn still in the whorl. Aster leafhoppers love lettuce, and there is a little damage but not bad. Tarnished plant bug is bad in strawberry varieties Kent, Northeaster and Earlyglow but Jewel, Cavendish and Winona look more resistant. (Shaftsbury)

Strawberries have just gone by (last small picking 6/23) and black raspberries are sizing up. Tarnished plant bugs are on the increase. Beets are being harvested and carrots will be ready soon, and no diseases at all due to the dryness. One bug that's nice to see is the lightning bug??thousands out there to light up the night. (Argyle NY)

The first major hatch of CPB mid-June was controlled with one spray of Bt. Some cuke beetle pressure on squash and cukes uncovered for pollination. First imported cabbageworm butterflies starting to lay eggs on brassicas. Greenhouse tomatoes ripening and will be picking first squash this week. (S. Royalton)

Massive invasion of cucumber beetles beginning to subside a little, interesting how some varieties are not destroyed, for example 'Vefyre' squash untouched. A few flea beetles showing up now. First run of CPB showing up. Stem borer attacked a few tomato plants but seems to have stopped. A little blossom end rot showing up in greenhouses. Hard to water often enough when the source comes from rain water. The weed battle goes on but I think we are getting ahead. Major cultivation of annual grasses in progress. Broadleaf weeds not such a problem in such dry conditions. (Charlotte)

Sales of potted herbs are good. Changed from 3" square web type pots to a single Classic 100. Costs a bit more in soil but grows a much better plant, and reduces watering frequency. Customers seem willing to pay an extra 20% for a bigger, better looking plant. Some grasshopper troubles in one greenhouse, very minor in the two greenhouses that froze all winter. Opening both ends and rolling up the sides prior to spraying garlic barrier helps drive them out. Achieved early control of woodchucks, but still lost several hundred feet of cilantro. Had big setback in basil production due to seed company error. (Thetford)

GREENHOUSE TOMATO MEETING at Crossroad Farm hosted by Tim and Janet Taylor on June 24 featured a 'blind' variety taste test. Scorecards were filled out by 18 participants. Big Beef was the clear winner. Buffalo, Grace, Blitz, and Match were the second tier. UltraSweet, Bounty, and Panther rated lowest. Tim explained that to avoid foliar diseases he no longer grows tomatoes outdoors, instead producing 27,000 pounds of tomatoes in 8 structures. The first greenhouse is planted around mid-March, when 6-week old transplants from 4-inch pots are set in the soil which has been sheet-composted with manure over the winter. He adds synthetic fertilizer and lays 2 drip lines per row. The next planting is one month later in a high tunnel with bottom heat, where fruit will mature about 2 weeks after the first planting. The next 6 tunnels, planted every 7 to 10 days, do not have bottom heat but all of Tim's tunnels do have permanent gas heaters, which he feels is necessary in cold climates with late frosts (June 15 this year). Plants are fertilized with calcium and potassium nitrate through the drip system. Mature plants get about a gallon of water per day. Pollination is still done by hand because Tim likes to get in there and see the plants (I'm a king bee, baby). In 16 years there has not been a major insect problem, perhaps because the houses are cleaned out and allowed to freeze every winter, and all tomatoes are started from seed on the farm. Blossom end rot is a problem sometimes, especially on the non-Dutch varieties. There are several styles of protected structures on the farm, but Tim's favorite now is a 21 by 96 with sides that go straight up 6 feet, a peak at about 10 feet, and end walls with doors that open up enough so a tractor can get in to spread manure.

PATRIOT BLUES: I've now seen 2 farms in Vermont where Patriot blueberries are declining, showing stunting, dead canes, and leaf distortion. On one farm, sick Patriots are easily identifiable even where they were planted as replacements in rows of other varieties. According to Marvin Pritts at Cornell, the suspect is tomato ringspot virus, although it is difficult to isolate from tissue samples. This virus is nematode transmitted, so transmission is slow. Theoretically it could put other nearby cultivars at risk, but it hasn't been seen this spread to other cultivars, which may be more resistant. Not much is known about cultivar resistance (i.e. nothing). The standard advice is to rogue out and destroy infected plants and fumigate or use a nematicide in affected areas. And, I wouldn't suggest planting any more Patriot.

ORGANIC RESEARCH FUNDS are available to study organic farming methods, disseminate research results to organic farmers and growers interested in making the transition to organic production, and to educate consumers on organic farming issues. Projects should involve farmers in design and execution, and take place on working farms when possible. Proposals of up to $10,000 are encouraged. Matching funds and/or in?kind contributions are recommended. Proposals are considered twice a year, the next round of proposals must be received by July 15, 1999. To receive copies of grant application procedures contact: Grants Program, Organic Farming Research Foundation, PO Box 440, Santa Cruz, CA 95061; 831?426?6606; e-mail: research@ofrf.org

SQUASH BUGS will be appearing soon, and you should scout for their eggs. Squash bugs overwinter as unmated adults under plant debris or other suitable shelter. When cucurbit vines start to run in spring, squash bugs fly into fields and mate. Over a period of several weeks, eggs are laid on undersides of leaves, typically in the angles formed by leaf veins. One or 2 weeks later, depending on the temperature, nymphs hatch from the eggs and begin to feed. Four to 6 weeks pass before nymphs develop into adults. Because of the prolonged egg-laying period, nymphs and adults are present throughout summer. Feeding continues until frost forces adults into hibernation. One generation occurs each year. According to Univ. Of Illinois, the threshold is estimated at 1 to 1.5 egg masses per plant in squash. Apply a labeled pyrethroid, carbaryl or neem product as soon as eggs begin to hatch. Specific insecticide recommendations and rates can be found in the current New England Vegetable Guide. The eggs are diamond or spindle-shaped, white when first deposited but gradually turn yellowish-brown and finally dark bronze. Eggs are approximately 1.5 mm long and 1 mm wide, arranged in a checker-like pattern, typically in masses of 20 to 40. The five nymphal instars range in length from 2.5 to 10 mm. The first instar is green with rose-colored legs, antennae, and head. These appendages darken in a few hours. Subsequent instars are grayish-white with dark heads, legs, and antennae. The last two instars have noticeable wing pads. All cucurbit vine crops are subject to squash bug infection. The bugs prefer squash, pumpkin, cucumber, and melon, in that order. Hubbard, winter, and marrow squash are often heavily infested. Feeding in colonies, adults and nymphs pierce vines with their needle-like mouthparts. While feeding, they inject a toxic substance into plants. As a result, vines quickly turn black and dry out. This aspect of squash bug damage superficialy resembles bacterial wilt symptoms. Small plants and individual runners of large vines are often destroyed. When infestations are heavy, fruit may not form. If fruit does develop, bugs may congregate and feed on unripe fruit itself. Good cultural practices help prevent serious squash bug damage. Proper fertilization of vines produce a vigorous crop better able to withstand insect attack. Removal and destruction of crop debris after harvest eliminates some potential overwintering sites for squash bugs. The bugs can also be trapped by placing small boards near the host vines. Squash bugs gather under the boards at night and are easily collected and destroyed the next morning. (Adapted from N. Carolina Extension)