Archived Newsletters

CROP CONDITIONS

After a week of very hot weather combined with wet conditions in the west and dry conditions in the east, we have seen a drastic reduction in temperature accompanied with quite a bit of rain. The rain has been good news for the east, as many farmers had not seen precipitation since the remnants of hurricany Cindi went through. Virtually all growers have started picking sweet corn as of this week. Many growers are picking peppers and a few have started tomatoes. This next week will prove to be a great growing week with adequate moisture and more average tempera­tures.

Rich Bonanno

SWEET CORN UPDATE

European corn borer second generation is here. We are seeing higher numbers in the E II across the state and are expecting to see some tassel damage in later corn as a re­sult. As the trap counts increase, scout corn that is tasseling for borer damage. When fields are 15% infested or over you know it is time to spray. Damage assessments made this week were still below threshold but we are keeping a close eye on green tassel corn. By using organic or less toxic materials you can let natural populations of benefi­cials increase to take care of any aphid problems you may have.

Corn earworm trap captures are still low. Trap captures in Sunderland and Deerfield were just above threshold at 3-4 moths caught per week. If you are catching more than 2 moths per week, a 6-7 day spray schedule is recommended (see table below). Drop nozzles with high pressure direct­ed at the silks are good for accurate coverage. Convention­al materials such as Warrior and Capture will work well in heavily infested areas. Spintor is less toxic and can be used in fields with low to moderate infestations. With the high temperatures we are experiencing, newly hatched larvae will move down silk and into the ears rapidly. Check traps twice a week to catch an infestation before it catches you!

Fall armyworm trap captures are still low this week. No worms have been seen in any field scouting. Those of you in the southeast should keep an eye out for damage since the first activity is usually found in that region of the state.

 

SWEET CORN TRAP COUNTS 7-22 TO 7-28

LOCATION	DATE		ECB Z1		ECB EII		CEW		FAW
Berkshires, W. MA/ Champlain Valley
Westeminster , VT	7-27		0		8		0		0
Brandon , VT		7-27		0		4		0
Pittsfield , MA	7-27		0		0		0		0
CT River Valley
Old Deerfield	7-27		5		101		4		0
Hadley	7-27		3		14		0		0
N. Hadley		7-27		5		45		4
Feeding Hills	7-25		3		6		3		0
C.& E. MA
Dracut	7-27		0		24		1		0
Still River	7-27		0		1		10*		-
Concord	7-25		0		5		2		0
Tyngsboro	7-25		3		2		1		0
Northbridge	7-25		0		9		4		1
Spencer	7-27		2		4		0		0
Monson	7-27		1		0		0		0
Dighton	7-27		1		2		11*		-
Seekonk	7-27		3		5		26		-
N.H.
Litchfield , NH	7-27		-		-		1		-
Hollis , NH	7-27		-		-		4		-
Mason , NH	7-27		-		-		1		-

 

*data taken from 2 traps

Article: A. Duphily

--Data: R.Hazzard, A.Duphily, B.Hunsdorfer, J.Mussoni

CORN EARWORM THRESHOLDS

 

Moths/Night	Moths/Week	Spray Interval
0 - 0.2	0 - 1.4	no spray
0.2 -0.5	1.4 - 3.5	6 days
0.5 - 1 days	3.5 – 7	5 days
1.0 - 13.0	7 – 91	4 days
Over 13	Over 91	3 days

 

 

CATERPILLARS IN BRASSICAS

Cabbage, broccoli, collards, kale and other brassica crops are showing feeding damage from imported cabbage­worm and diamondback moth. Fortunately, cabbage looper has not been observed much yet, which is not suprising since the same conditions that bring corn earworm would bring us this migratory moth. The collective group of three caterpillar types – generally known as ‘worms in cabbage’ – can be quite confusing. They differ in size and feed­ing habits, as well as how susceptible they are to certain insecticides. All can cause damage to leaves and heads of brassicas. Below are descriptions and photos.

Imported cabbageworm; cabbage butterfly (Pieris rapae). This familiar white butterfly can be seen in the daytime fluttering around brassica fields. Each forewing has a dark border and one or two round black spots. Eggs are laid singly on the underside of leaves, about 1/8 inch in length, light green or yellow and slightly elongated, stand­ing upright. The larva, called imported cabbageworm, is gray-green, fuzzy, and sluggish. It has thin yellow and white stipes on the top of its back. Feeding and resting occur mostly on the underside of leaves, though you may see them on the top of inner leaves of the plant. Caterpil­lars feed more heavily in the center or head of cabbage or broccoli as they grow and leave wet frass as well as large holes. You may find the crysalis (pupa) which is green or brown, smooth with three pointed ridges on its back, on the underside of the leaves. This is stage that over-winters, and emerges as a butterfly early in the spring. There are 3-4 generations per year.

Diamondback moth (Plutella xylostella) caterpillars are smaller, light green, appear more segmented and more pointed in shape. When disturbed they wiggle vigorously and may drop off the plant on a string of silk. Feeding causes small, round holes and tends to be spread across the foliage and not necessarily concentrated in the head. The adults are tiny (<1/2 inch), light brown, and rest with their wings folded together like a tent. They overwinter in crop residue, but may also enter the region by migrating from southern states or on transplants bought in from other regions.

Cabbage looper. Cabbage looper usually does not survive the winter in New England, and arrives in migra­tory flights from farther south. Generally numbers are not significant until late July. However, earlier flights do occur, probably as a result of early migratory flights. Adult moths are mottled gray-brown, about 3/4 inch long, with a distinct round silver-white mark on each fore-wing. They are about the same size as corn earworm moths. Since they fly at night, they are rarely seen unless monitored with pheromone traps. The recommended trap is the rigid bucket type, either a Multipher or a Unitrap, baited with either Trece or Scentry lures for Trichoplusia ni. Place the trap at foliage height, and secure the lure under the lid. Use an insecticidal vapor strip (Vaportape) so that moths die before their wing scales are damaged -- otherwise they can be difficult to identify. Sources for traps and lures include Great Lakes IPM (517) 268-5693 and Gempler’s (800) 382-8473. Typically we find a variety of non-target moths in these traps, but the coloration is generally quite different. However, celery looper has only a slightly different wing marking from cabbage looper. Feel free to contact the UMass Vegetable IPM office (413-545-3696) if you have questions on traps or identification.

The cabbage looper caterpillar is light green, smooth-bodied, with wavy white or light yellow lines down the back and sides. Full-grown larvae reach 1 ½ to 2 inches. At rest or when disturbed, cabbage loopers of any size will raise the middle of their body in a characteristic “loop” shape. Feeding tends to create ragged, large holes in foli­age, on both frame leaves and heads. Eggs are round, light green or yellow, and laid underneath the foliage. Monitor caterpillar activity by field scouting (below).

Field Scouting for caterpillars: It is important to check cabbage, broccoli, and cauliflower plantings as they begin forming heads. Greens such as collards, kale, and Chinese cabbage should be scouted earlier, since all leaves are marketed. The waxy cole crops tend to be more heavily attacked by these caterpillars than the non-waxy Asian greens, but that does not mean that greens should not also be scouted. Mustard is a favorite of diamondback moth.

Being somewhat systematic helps you decide when you do –and do not—need to spray. Check at least 25 randomly-selected plants throughout the field looking for caterpillars on the top or underside of leaves. Feeding damage can be found on the underside of leaves or in the center of the plant where heads are forming. Often it is easier to spot the feeding damage first, then find the caterpillar –especially when the caterpillars have just hatched. Classify plants as infested (has one or more caterpillar) or non-infested, and calculate the percent of plants infested. Spray if the thresh­old is reached.

It should be noted that these thresholds do not imply that 10 or 15 % of the harvested crop will be infested! They are based on research trials that showed that use of the thresholds produces 98-100% clean heads, a quality that is the equivalent of what you get with weekly sprays but with far fewer insecticide applications. Greens have a lower threshold because the leaves are the part of the plant that is harvested.

Action thresholds for caterpillars in crucifers

 

Crop & Stage	% Infested Plants
Cabbage, Broccoli, Cauliflower
pre-cupping (before head formation begins)	35%
Cabbage & broccoli
head formation to maturity	15%
Cauliflower
After heading (before tying)	10%
Kale, collards & other greens	10-15%

 

Caterpillar controls

See the New England Vegetable Management Guide (in print or on the website www.nevegetable.org) for specific recommendations. There are several types of ‘biorational’ insecticides available for these caterpiallars: safer for the handler, short pre-harvest interval, and easier on benefi­cial insects. These include indoxycarb (Avaunt), spinosad (Spintor 2SC or Entrust, which is OMRI listed), Bt kurstaki (eg Dipel DF, Biobit HP, Javelin WG, Deliver, which are OMRI listed), Bt aizawi (Agree WG, Xentari DF, Xentari WDG –all OMRI listed), all of which must be ingested though some, such as spinosad, also have contact toxicity. Confirm, (tebufneozide an insect growth regulator), Intrep­id (methoxyfenozide, which causes premature molting) and Proclaim (emamectin benzoate, an avermectin, derived from a bacterium) also would be classified as reduced-risk materials. Note that days to harvest intervals vary. A number of synthetic pyrethroids are labeled and effective though they are more likely to result in aphid outbreaks from reductions in beneficials.

It is wise (and easy, in this case) to rotate among differ­ent classes of insecticides which can include rotating the two types of Bt to reduce the chances of selecting for resis­tance to one type of insecticide. Diamondback moth, in par­ticular, has a history of developing resistance. Fortunately, in central and northern New England it is not present in the huge numbers that are found in southern and tropical areas.

Use of spreader-sticker type adjuvant is advisable when applying to the waxy leaves of brassicas.

--Ruth Hazzard

FLEA BEETLE UPDATE

Flea beetles have begun emerging again -- new adults that are the offspring of overwintering beetles you saw in May and June. These beetles are hungry and will feed heav­ily on both cole crops (eg fall broccoli) and Asian brassicas (fall greens) especially if these are close to the location of the spring crop. If possible put fall plantings far from the spring crop.

Provide protection: row covers (light weight if pos­sible for August plantings; heavy covers may be too hot) or insecticides. Some of these beetles will lay eggs. We are seeing a mixture of the all-black crucifer beetles and the striped flea beetle.

It is possible that a similar life cycle occurs with eggplant flea beetle. If so, watch egg­plants for two major pests that will be emerging soon: Colo­rado potato beetle adults and eggplant flea beetle. This flea beetle is black but more chunky in shape than the cru­cifer flea beetle, and they have distinctly different tastes!

--R. Hazzard

BACTERIAL CANKER AND SPECK OF TOMATOES

Bacterial canker: typical symptoms on foliage are “scorching” of leaf margins -- brown, crisp edges of the leaves, with a thin, yellow chlorotic band inside the burned tissue. This “secondary infection” is what we see most often. Fruit may have “bird’s eye” spots, small raised scars with a tiny brown center surrounded by a white halo. Symptoms of systemic infections include stunting, wilting (especially one half of a compound leaf), development of open stem cankers and fruit lesions. Canker can be seed-borne. The Clavibacter bacteria can survive for at least one winter in crop residue on the surface or underground, and will infect successive crops in non-rotated fields (this includes ‘rotated fields’ that are adjacent to last year’s tomato fields). Greenhouse equipment and field stakes can also be sources of the bacteria. A single tomato variety with very low levels of infected seed can infect all the rest, either in the greenhouse or in the field. Non-symptomatic transplants can carry the bacteria on external leaf surfaces, and these bacteria can enter the vascular system through wounds and natural openings. They can also be spread through the field by rain or moist wind, workers, and airblast sprayers. Wherever possible, use drop nozzles on a boom sprayer in staked tomatoes, and a boom over ground tomatoes. Weekly copper applications (Kocide, Champ) suppress the development, but should start when symptoms first appear. Scouting and early identification is key in eradicating bacterial canker.

Bacterial speck: Symptoms of speck are tiny black spots on leaves, which soon develop a yellow halo. Small black specks can also be seen on fruit. Leaves with a lot of spots usually turn yellow and fall off. This disease is seed born and when wet weather comes along, the disease can really get going. Splashing water from heavy rains will spread the disease easily. When the leaves are wet, bacte­rial speck is easily spread by tractors or people as well.

If either of these bacterial diseases is present, applica­tions of copper on a weekly schedule are recommended to reduce the spread of the disease. If possible, applications should be made with a boom sprayer, as an airblast sprayer can spread the bacteria to new locations in the field. If possible, harvest infected fields only when they are dry to avoid spreading the disease.

--R. Hazzard

ECB IN PEPPERS

Eggs are laid on the undersides of leaves and the young larvae enter the fruit by burrowing under the fruit cap. Signs of ECB infestation include darkened tissue, frass or small white larvae under and around the calyx (see photo).

More areas in the state have above threshold levels of European corn borer this week (>7 moths/week). ECB levels do vary quite a lot from field to field, so if trap captures near you give conflicting results (above threshold here, not there), consider the fields where your peppers are: if you’ve had rain and generally get a lot of ECB in that field err on the side of caution and begin your sprays next week, since they should begin the first week after threshold is reached. The week delay allows for mating, egg-laying and egg hatch to occur so that the eggs and larvae can be targeted before larvae enter the fruit.

Choosing less toxic or microbial products to control ECB is recommended to preserve beneficial predators in the field. SpinTor 2SC and Entrust (both spinosad formulations) have proven to be good products to use for ECB control. They have low toxicity to mammals and are considered reduced risk materials. Both have the advantage of conserving beneficial insects such as ladybeetles which feed on aphids which can be a problem later in the season. Both products also have a one-day pre-harvest interval and a four-hour re-entry interval which make them particularly useful for farm stands and small plantings which are picked frequently. Bacillus thuringiensis kustaki (BT) can also be used on a 3-to-4 day scheduled throughout the 2nd generation.

Another way to control ECB in peppers is to release the parasitic wasp, Trichogramma ostriniae. Since the wasp doesn’t stay in the peppers as well as it stays in sweet corn, weekly releases for 3 or 4 weeks is necessary. Begin the releases when ECB flight starts, or soon thereafter- so order now! Trichogramma ostriniae can be obtained through

IPM Laboratories, Inc.

Phone: (315) 497-2063

Fax (315) 497-3129

E-mail: implabs@ipmlabs.com

or visit: http://www.ipmlabs.com

For other conventional methods of ECB control in peppers refer to the 2004-2005 New England Vegetable Management Guide.

 

KEEP AN EYE OUT FOR SOYBEAN APHID

The soybean aphid was reported for the first time in Massachusetts last year on one farm in Franklin County and one farm in Hampshire County. Since the discovery of the soybean aphid in the Midwestern United States in 2000, the soybean aphid has been found in 23 states including New York, Connecticut, and Maine. The soybean aphid, a native of China, requires two hosts to complete its life cy­cle. The soybean aphid lays eggs on buckthorn species in the fall where they will overwinter. In the spring the aphid undergoes two wingless generations before winged females seek out soybean plants. The soybean aphid is a pale yel­low aphid with black cornicles (the “tailpipes” sticking out of the rear of the insect). Although the soybean aphid is similar in appearance to the melon aphid (Aphis gossypii), it has a much narrower host range attacking buckthorn (Rhamnus spp.), soybean, and a few clovers. The soybean aphid can be a vector of soybean mosaic virus.

When aphid populations become extremely high, soy­bean plants may yellow and become stunted, reducing plant yield. The current economic threshold established for soybean aphid is 250 aphids per plant. On September 10th last year a scout reported the densities of the Massachusetts’ sites to be 100-200 aphids per plant. Spraying for aphids before the threshold is reached increases the risk of popula­tion rebound and eliminating any yield gain due to insecti­cide application. A number of natural enemies are present that will prey upon the soybean aphid such as ladybird beetle adults and larvae, damsel bugs, minute pirate bug nymphs and adults, syrphid fly larvae, and spiders. In di­versified farms or areas these natural enemies will do a lot to keep the soybean aphid under control and may prevent it from reaching population levels that will affect crop yield. It is possible that the threshold will never be reached and no action will be necessary to protect the soybean yields.

If you are growing soybeans keep on eye out for soybean aphids on your plants. When the first report of soybean aphids is confirmed for Massachusetts, I’ll inform Veg­etable Notes readers and post the information on the Mas­sachusetts Introduced Pests Outreach Project website at http://www.massnrc.org/pests.

The following sources provide detailed information about soybean aphid and management options for this pest:

• Soybean aphid, Ontario Ministry of Agriculture, Food, and Rural Affairs

http://www.gov.on.ca/OMFRA/english/crops/facts/soyaphid.htm

• Soybean aphid Basics, Plant Health Initiative

http://www.planthealth.info/aphids_basics.htm

-- Julie Callahan, Massachusetts Department of Agricultural Resources

 

CANCELLATION OF LAST VEGETABLE USES FOR RONILAN

Vinclozolin, the active ingredient in Ronilan, is a di­carboximide. This group of fungicides has been among those targeted by EPA for review. EPA has been reviewing potential human health and environmental effects of older pesticides since FQPA (Food Quality Protection Act) was enacted in 1996. This reregistration process has resulted in the voluntary cancellation by registrants of some pes­ticide uses, mostly to reduce risks and improve safety of uses allowed to continue in order to meet the FQPA safety standard.

Ronilan was first registered in the US in 1981. Veg­etable uses were for the fungus Sclerotium (white rot) and Botrytis (leaf blight and neck rot) on onion. In 2000, the registrant, BASF, proposed to EPA to add to the label suc­culent beans and canola. EPA determined it could not make the ``reasonable certainty of no harm’’ finding mandated by section 408(b)(2) of the Federal Food, Drug, and Cosmetic Act (FFDCA) for these new uses and associated tolerances if all existing uses remained in place. BASF requested immediate termination of use of Ronilan on onion and phase out over 4 years of the other food uses except canola. A supplemental label was issued for Sclerotinia (white mold) on snap beans. The last date for sale and distribution of ex­isting stock of Ronilan EG (EPA Reg. No. 7969-85) for use on lettuce and snap bean is July 15, 2005 for the registrant and September 30 for distributors and others.

The last date for legal use is November 30, 2005. Ronilan DF Fungicide (EPA Reg. No. 7969-85) is still currently registered in “discontinued” status with a supple­mental label for snap beans. None of this product is thought to exist in the channels of trade. Its registration will be suspended when review of the Ronilan renewal application is complete. For additional information see: http://pmep.cce.cornell.edu/profiles/fungnemat/tcmtbziram/vinclozo­lin/vinclozolin_cancel_801.html.

Fortunately Endura (EPA Reg. No. 7969-197), a new fungicide registered by BASF, is anticipated to be a suitable replacement. It is labeled for Botrytis leaf blight and purple blotch in onion and other bulb crops; Botrytis rot as well as Sclerotinia drop in lettuce; Botrytis gray mold and rust as well as Sclero­tinia white mold in bean; and it is labeled for use on carrot (Alternaria leaf spot), potato (early blight and white mold), and tomato and other fruiting vegetables (early blight and Botrytis gray mold). Other options for managing white mold are the biological fungicide Contans, or Topsin M (alone or combined with Endura or Rovral for snap and dry beans, or with Bravo for snap beans only), and Rovral for lettuce. A tank-mix of Endura at 5.5–5.9 oz/A or Bravo WS at 1.5 pt/A with Topsin M at 11.2 oz/A has provided good control of both white and gray mold of snap bean in experi­ments conducted in Geneva, NY.

--Margaret McGrath

Long Island Horticultural Research & Extension Center, Cornell

 

GET YOUR TOMATOES READY FOR THE 2005 MASSACHUSETTS TOMATO CONTEST

Farmers from across Massachusetts will go stem to stem at Boston’s City Hall Plaza, Monday, August 22nd during the New England Vegetable and Berry Growers Association’s 21st Annual Tomato Contest. This friendly competition is designed to heighten awareness of one of the most popular local crops of the summer months – tomatoes.

Chefs, food writers, produce buyers and other experts will judge the tomatoes on flavor, quality, color and shape, with categories including slicing, cherry, heirloom and heaviest.

Growers are encouraged to bring in their tomatoes to the contest on the 22nd or drop off their tomatoes at one of five locations across the state. Tomatoes dropped off, will be brought into Boston the day of the contest.

For more information, and a list of drop-off locations and registration information go to http://www.mass.gov/agr/markets/tomato_contest.htm or contact David Webber at 617-626-1754 or david.webber@state.ma.us

Vegetable Notes, Ruth Hazzard, editor and Ben Hunsdorfer, Assistant Editor. Vegetable Notes is published weekly from May to September and at intervals during the off-season, and includes contributions from the faculty and staff of the UMass Extension Vegetable Program, other universities and USDA agencies, grow­ers, and private IPM consultants. Authors of articles are noted; author and photographer is R. Hazzard if none is cited.

Where trade names or commercial products are used, no com­pany or product endorsement is implied or intended. Always read the label before using any pesticide. The label is the legal document for product use. Disregard any information in this newsletter if it is in conflict with the label.