VERMONT VEGETABLE AND BERRY NEWS, April 15, 2002
Compiled by Vern Grubinger, University of Vermont Extension
(802) 257-7967 or vernon.grubinger@uvm.edu
www.uvm.edu/vtvegandberry

REPORTS FROM THE FIELD (as of April 9)

Starksboro:  The ground is no longer frozen. I have been doing some frost seeding of clover.  I am starting to do some early plowing. Despite the fact that the ground is thawed already I still do not plan to plant peas for another couple of weeks as I find that due to poor germination and few growing degree days there is little or no gain to planting before April 22 or so.

Fairlee: our Lithuanian J-1 student arrived Friday and is now bustling around our greenhouses. I’m sending soil samples into UVM from our in-ground greenhouse tomato houses. Garlic is poking up through the straw, fields drying out almost too fast. The pond is almost full.

W. Rutland: Winter rye is growing slower than last year. Areas that had standing water  even for 2 days has killed the rye. Land is still a bit wet to plow but will attempt it soon. The greenhouse is rocking.

Grand Isle: A warm, relatively dry winter made the job of raking straw off the strawberries and sweet william on April 6. A rewarding and easy job. ‘Rewarding’ because there does not appear to be any winter kill, ‘easy’ because it was so light and fluffy we were able to move along at a nice clip. We then covered the earliest variety of berries with floating row cover. A terrific wind about three weeks ago lifted up one side of a tomato hoop house and made a big mess of things.  Three days of repairs has restored it to working order. Greenhouse plantings and general spring clean up dominates most of our time. We have talked about burning the last year's asparagus ferns but conditions have not been right yet to get a permit and do the job.

Argyle NY:  Our first seeding of peas, radishes, and turnips went in the ground on March 31st with row cover, and they are all just germinating; second larger seeding including carrots, beets, etc. went in today.  Lettuce and spinach is on it's 7th seeding with some transplants in fieldhouses (unheated hoop houses) which will hopefully be ready for our markets that open May 1st.  It's good to get rain as we're very dry already. Strawberries have tight flower buds showing.  Lots of peepers but no pests yet!

Putney: Greenhouse tomatoes are growing well, set in ground early March, now almost 6 feet tall. The second truss didn’t set due to cloudy weather. Grafting seedlings now for later plantings. Early cucumbers are coming in, have 30 plants, eating a lot selling a few. The usual pests, a few aphids, a few thrips, no whiteflies yet, nothing extreme. Introducing beneficials as needed.

Glover: Our 4 week old greenhouse tomato seedlings froze when the furnace quit on Saturday night. So, we are looking for a source of seedlings of Buffalo tomato to replace them. We can be reached at 802-626-3146 or e-mail backacres@hotmail.com Carl Benson, Backacres Farm

Westminster: I have issues with my compost potting soil and I’m having many problems in the greenhouse. I  sent samples off yesterday to UVM for a saturation media test. I really should and will be testing each load I get. I still haven’t found an organic potting soil that’s ready to use without having to add nutrients or dilute it with peat or vermiculite. Besides that things are going well, just finished building some cold frames and planing on adding greenhouses later this
summer if all goes well!

Amherst MA: Field conditions are generally dry, but not overly so - we've been able to plow up the early fields with no problems, but noticing usual wet spots not so wet. No trucks or tractors stuck yet. We've got about 5 acres ready for planting and look to start first seeding (peas, spinach, chard and onions) this week. The greenhouse is growing well and almost full. Trucks and tractors getting into field shape. Marketing (selling CSA shares) is faster than usual (up about 10% from past pace) and looks like we'll sell out a couple of weeks earlier than usual. All in all, a pretty smooth start to what could be a very dry year....but who knows?

Saunderstown RI:  Spring on the coast is cool and blustery as usual. Our greenhouses usually take a beating but it does dry up the fields nicely, especially this year. We have  most of the spring and summer fields plowed and are trying to muster more energy to finish pulling the rocks out so we can plant. Gotta love that 7-shank chisel plow for quick plowing and bringing rocks to the surface. The greenhouses are filling up. Carrots and beets were planted in March for an early June CSA harvest and the seedlings are doing well. Green slime on the soil surface is our only problem but it doesn't appear to be life threatening. This is an annual problem.

HERBICIDE RESIDUES CAN CONTAMINATE COMPOST
(adapted from Washington State Univ. press release)

In 2001, a new source of contamination, clopyralid, was discovered in compost in Washington and Pennsylvania. This is the active ingredient of an herbicide sold as Confront for use in turf, Curtail for use in cereal grains, Stinger for use in sugar beets, mint, and asparagus, Lontrel (Canada) for use in strawberry, blueberry, and balsam fir Christmas trees, and other formulations. This chemical is persistent and can pass through animals and through the composting process with little breakdown. Warnings on the label say not to use treated crops for mulch or compost in the year of application. Studies indicate the toxin can remain active after two or more years of aggressive composting. So, be careful if you make compost using grass clippings, grass hay or straw from unknown sources. Contamination can also occur from livestock bedding that includes treated material or from manure if treated crops have been fed to livestock.

Clopyralid is extremely toxic to legume crops such as peas and beans, tomatoes, potatoes and sunflower at levels of about 10 parts per billion (ppb) or less. This level is 100 times lower than the tolerance allowed on asparagus, 50,000 times lower than the tolerance allowed on grasses, and 300 times lower than allowed on barley grain. These tolerances are seldom seen in the real world, but these allowable levels point out the potential for inadvertent contamination to sensitive crops. Because of the relatively high tolerance allowed for human safety, most labs do not routinely measure clopyralid below 50 ppb. Consequently, potentially-injurious levels in straw, hay, compost, and other residuals are often not detected.  The simplest way to know if  your compost is safe for crops is to test it ahead of time by growing several sensitive species in ‘bio-assay’ plantings. For more information see links from: www.grrn.org/dow/background.html

RED STEELE RESISTANT STRAWBERRIES

To avoid the destructive root disease called red steele, avoid planting in wet fields and select  resistant varieties. According to the NY Berry News, resistant varieties in the northeast are: Allstar, Annapolis, Cavendish, DelMarvel, Earliglow, Idea, Guardian, Lateglow, Midway, Mohawk, Northeaster, Primetime, Redchief, Scott, Sunrise, Tribute, Tristar, and Winoma.

RASPBERRY PRUNING AND DISEASE MANAGEMENT
(adapted from NY Berry News)

Dormant pruning should be underway if not complete by now. In addition to removing all of last year’s floricanes, taking out any weak spindly canes, and those showing signs of winter injury, all diseased canes should also be removed and destroyed. Early season removal of diseased canes before new canes emerge is key to controlling the cane diseases anthracnose, spur blight and cane blight. These all cause purple lesions on the canes. Anthracnose appears as small purple spots scattered on young canes and tends to be worse on black and purple raspberries than reds. Spur blight is centered on individual buds and appears as purple to brown blotches in mid-summer. Infection often occurs early and infected buds fail to grow even though other symptoms are not evident. Cane blight is much more of a problem on red raspberries. It can be confused with spur blight but it tends to involve the entire can, not just the buds, and infection is typically associated with pruning wounds or injury. After pruning, a dormant application of lime sulfur or copper is critical where any of these diseases are a problem. Spray on a calm day and be sure to get complete coverage of the canes. Don’t delay, as this spray may injure plant tissue if applied after ½ inch green, especially on a warm day. See the New England small fruit management guide for details.

RESISTANCE  MANAGEMENT  ESSENTIAL  WITH STROBILURIN  FUNGICIDES
(adapted from an article by Meg McGrath, Cornell)

Strobilurin fungicides can be a valuable tool for managing diseases. They are effective against many plant pathogens, and they can move through treated leaves to provide control on both leaf surfaces. They have been designated 'reduced risk' pesticides by EPA. Azoxystrobin, formulated as Quadris and Abound, was the first fungicide in this group to be registered. Trifloxystrobin, formulated as Flint, Stratego, and Compass, was the next. Pyraclostrobin, formulated as Cabrio EG and Headline, is expected to be registered soon. Quadris is now registered for use on almost all vegetable crops against a wide variety of diseases. However, resistance risk with strobilurins has proved to be higher than expected and more difficult to predict. For example, resistant strains of the cucurbit powdery mildew fungus were found in 1999 after just two years of commercial use. To manage resistance to strobilurins, limit their use and use them as a component of an integrated program with other fungicides and non-chemical management practices, such as resistant varieties and rotation. This is the standard approach for managing fungicide resistance.

The goal is not to manage resistance once it has developed, but rather to prevent or delay development of resistance. Apply strobilurins in alternation with other systemic fungicides registered for the target disease that have a different mode of action. Do not alternate among strobilurins because they all have the same mode of action. The fungicide program should also include fungicides with a low risk of resistance, such as chlorothalonil and copper hydroxide. No more than a third to half of the applications in a season should include strobilurins. Since they have outstanding ability to inhibit spore germination, strobilurins should be most useful early in disease development. Use a disease threshold or a disease forecasting system such as TOM-CAST, when available for the target disease, so that the first application is made at the most critical time. Consider using contact fungicides alone at the end of the season.

(Mention of pesticide names is for educational purposes only, no endorsement is intended. Always read and follow the label.)