REPORTS FROM FIELD TO START NEXT ISSUE
It's almost time for the first "reports from the field" of 2000. I will be sending an e-mail reminder asking for reports from growers every two weeks, a day or two before the next Vermont vegetable and berry page is due to the printers for the hard-copy edition in the ‘Agriview' newsletter. Let me know at any time if you would like to be removed from this e-mail list. For those of you new to this, reports from the field should be a paragraph or less, describing current crop conditions, field activities, pest population, and/or comments on markets or other items or interest to growers. Reports specifying percentages of a crop infested or damaged by a particular pest would be appreciated. Some humor doesn't hurt, either. I will select and edit the reports to make them fit in the allotted space.
SMALL FRUIT GUIDE UPDATE (from Sonia Schloemann, UMass Extension)
Sorry, but the 2000 -2001 New England Small Fruit Pest Management Guide will not be available until June. Orders for the guide from members of the Vermont Vegetable and Berry Growers Assn. will be filled as soon as I get them. Meanwhile, here is a list of the most significant label changes affecting pest management practices in small fruits. Please continue to use your 1998-1999 guide this spring, consulting the list below for exceptions to the "old" recommendations. Rates and timing are not included; consult the product labels.
General small fruit fungicide label changes: Benlate (benomyl) - While not new, it is important to emphasize that the current Benlate label specifically states that Benlate is "not for use in home plantings nor once any commercial crop is turned into U-Pick, Pick Your Own, or similar operation." Some states have a more strict interpretation of this requirement than others. Captan - Also not new, but worth reminding growers that Captan has a 0 day PHI, but the REI of 24 hrs requires that PPE be worn during this period.
Strawberry insecticides: Additions: Sunspray Ultrafine Oil (paraffinic
oil) for twospotted spider mites; Pyrenone Crop Spray (pyrethrins) for
clipper, tarnished plant bug and spittlebug (esp. for organic production
systems); commercial formulations of parasitic nematodes for root weevils;
Deletions: Morestan (oxythioquinox) for twospotted spider mites since it can only be used on non-bearing beds. Label Changes: Guthion (azinphos-methyl) REI changes to 48 hrs for mowing, irrigating, and scouting and 4 days for all other activities. PHI is still 5 days. Danitol (fenpropathrin) label now includes strawberry sap beetle. Strawberry fungicides: Additions: Elevate (fenhexamid) for Botrytis gray mold management; Deletions: Ronilan (vinclozolin) for Botrytis gray mold management; Benlate (benomyl) for Botrytis gray mold. Label changes: Rovral (iprodione) can only be used before bloom, which eliminates its usefulness for Botrytis Gray Mold management. Strawberry herbicides: Additions: Goal 2XL (oxyflourfen) as a preplant weed control for many annual broadleaf weeds; Scythe (pelargonic acid) for emerged annual weeds and suppression of perennial weeds; Other: Dacthal (DCPA) remains in the recommendations with the expectation that production will resume and the label continue to be in effect.
Blueberry Insecticides: Additions: Pyrenone Crop Spray (pyrethrins) for cranberry and cherry fruitworm and blueberry maggot (esp. for organic production systems). Label changes: Guthion (azinphos-methyl) REI changes to 48 hrs for mowing, irrigating, and scouting and 4 days for all other activities. PHI is still 7 days. Blueberry Fungicides. Additions: Check with your state's Pesticide Office for Section 18 emergency registration for Orbit (propagonizole).
Here are short summaries of variety trials that have been conducted by Dr. David Handley, Maine Extension. The trials were described in the most recent edition of Yankee Grower, from University of Connecticut. Fourteen sugar-enhanced (se) bicolor corn varieties ranging from 62 to 80 day maturity were compared. Lancelot, Wizard and Sweet Symphony produced the highest quality ears but were late maturing. Double Gem, Seneca Arrowhead and Sweet Chorus produced good quality, earlier maturing crops. Of the 8 leaf lettuce varieties compared, Crisp&Green was the best overall performer, having a uniform stand, upright structure, medium green color and large size. Simpson Elite and Two Star also had large head size. Eight zucchini varieties were compared. Exel, Green Eclipse and Spineless Beauty produced the highest yields with good to excellent fruit quality. Contact me for copies of articles describing details of the trials.
GREENHOUSE TOMATO FRUIT SET PROBLEMS (adapted from veg-prod listserve)
Assuming pollination is adequate there are several other causes of poor fruit set in greenhouse tomatoes. High N and low K fertility can both lead to decreased flower production, i.e. a more vegetative plant. Excessive fruit load may also cause problems. With 5 or more fruit in the first cluster, the strong ‘sink' for carbohydrates in this cluster can reduce set in clusters higher up the plant. It is better to cluster-prune to reduce fruit number to about 4 per cluster all the way from the first cluster to the top. At times, 3 fruit per cluster may be required to keep plants productive all the way up. If your plants are already overloaded, remove ripening fruit from first two clusters as soon as possible and cluster prune higher clusters to 3 or 4 fruit when fruit reach marble size. This also is an opportunity to selectively remove cull fruit when they are very small, leaving only the marketable fruit to develop fully. Another possible cause of poor fruit set is high EC (conductivity) in the root zone, as a result of over fertilization leading to high salt levels which can make flowers drop. Also, if there is a problem with the heating system such as a small leak in the chimney/vent or a system that is not properly tuned, traces of ethylene gas in the house can cause abortion of the blossoms. Answers to Greenhouse Tomato FAQ (Frequently Ask Questions) are at http://ext.msstate.edu/anr/plantsoil/vegfruit/tomato/ghtomato/faq.html
RASPBERRY CROWN BORER CONTROL (adapted in part from Illinois extension)
In the past diazinon was sometimes used for raspberry crown borer control as a soil drench around the base of plants early in the spring. Diazinon is no longer labeled for use on raspberries, and only "old" containers specifically labeled for such use may be "used up" in this way. Remove and destroy infested canes and remove nearby wild brambles to reduce future problems with this insect. Sniper 2E is also listed in the small fruit pest management guide for control of crown borers - this should be applied as a heavy drench before harvest. Some trials of soil drenches using insect-pathogenic nematodes as biological control agents have been successful against crown borers. These nematodes infect and kill only insects, not plants or other organisms. Mike Cherim of The Green Spot (603)942-8925 recommends applying several drenches of Hb nematodes (Heterohabditis bacteriophoba) a couple of weeks apart. Since overwintered larvae may be moving around from cane, to crowns to roots in the spring, this would appear to be a good time to apply nematodes. Use 1 million nematodes (about $13) per 2,000 sq. ft. of row area to be drenched. Cost to treat an acre (25 million nematodes) is about $116.
NEW BIORATIONAL PESTICIDE - SURROUND WP
Recent research by USDA has led to the development of an insecticide that works by leaving a clay particle film on leaf surfaces. The commercially available product derived from that research is now being sold as Surround WP by Engelhard Corp. This material is 95% kaolin (clay), formulated to leaves a white-colored film on plant surfaces that is moderately effective as an insecticide and as a fungicide. Initially developed for use on tree fruit, Surround WP is labeled for suppression of plum curculio, leafrollers, leafhoppers, apple maggot, first generation codling moth, thrips, and for control of pear psylla. It is also labeled for use on vegetable crops, including suppression of CPB, flea beetles and leafhoppers on tomato, eggplant and pepper; suppression of onion thrips on onions, and suppression of cucumber beetles on cucurbits. Surround is labeled for small fruits (only if they are to be used for processing), including suppression of Japanese beetle, leafhoppers and thrips on blackberries, raspberries, blueberries and wine grapes.
Surround should be applied to dry foliage as a fine mist, using 25 to 50 lb per 100 gallons of water and an air blast or high pressure sprayers to assure good coverage and adhesion. Re-application is necessary when the dry foliage has lost its white appearance, generally every 7-14 days. Heavy rain, rapid foliage growth and wind erosion will affect film quality and may require reapplication. Washing of crops is usually necessary to remove the clay film unless it weathers off before harvest. The REI is 4 hours, and the pre-harvest interval is 0 days.
More research is needed before commercial growers switch from conventional insecticides to this product, but they may wish to trial it, and those who do not use conventional synthetic insecticides may find it to be an alternative to more toxic botanical pesticides. Surround was recently approved by OMRI and is OK for use in most certified organic production (check with your certifying agent). UAP is the regional distributor, with locations including Sterling, MA: (978) 422-3331; Lewiston, ME: (207) 795-6640 and Vergennes, VT: (802) 759-2022. Mike Brinkman at UAP tells me it will sell for about 80 cents/lb, with volume discounts available.
The pyrethroid Danitol (fenpropathrin, from Valent) is now labeled for use on cole crops, melons, and tomatoes. Target pests in cole crops include cabbage looper, imported cabbage worm, cabbage webworm, yellowstriped armyworm, and diamondback moth (only at the higher rate listed only for Brussels sprouts and cauliflower), cabbage aphid, green peach aphid, and whiteflies. Target pests in melons include fall armyworm, twospotted spider mite, and whiteflies, and in tomatoes include twospotted spider mite, whiteflies, several Lepidopteran species (caterpillars), thrips, aphids, and stink bugs. Preharvest intervals are 3 days for tomatoes and 7 days for cole crops and melons.