Pest Alerts

8/21/03

CROP CONDITIONS
---R Hazzard, contributions from J. Golonka, D. Rose, K Foppema, W. Czajkowski, NASS Crop Weather 8/18/03

Lower humidity, cooler nights and fewer rainstorms have been a welcome change this week. The continued hot sunny days are good for ripening and growth in fruiting and vine crops. Some crops such as cabbage are coming in full of water, which sometimes causes splitting – even after harvest. Pumpkins and winter squash are beginning to ripen in some fields, while late plantings are still setting and growing fruit. Everyone hopes for a warm, sunny September and a late frost. Late summer squash and zucchini plantings are ready to produce a fresh harvest. Potato vine kill and harvest is underway. Late plantings (seed and transplant) of fall greens are going in (and might even need irrigation), and fall crops are growing well. Growers are catching up on weeding and cultivating. Some growers are preparing for the loss of student workers who will leave after Labor Day.
Growers are finding some wormy corn despite intensive spray schedules, but corn earworm pressure is easing off a bit. European corn borer feeding damage in peppers and corn is likely to increase in the next week or two, as eggs from the second flight hatch. Phytophthora capsicii is showing up widely in vine crops, peppers, and tomato, as are other diseases. Sales are strong in retail markets. Several cases of Plectosporium in zucchini have been confirmed (in both eastern and western MA) since last week’s alert. If you think you might have this disease in zucchini or pumpkin contact R. Wick.

8/21/03

SWEET CORN
R Hazzard with contributiosn from A. Duphily, J. Golonka, B. Howden, J Mussoni, D. Rose, R. Pestle,P. Westgate, and P. Willard

Corn earworm captures declined this week throughout the region – but numbers are still high. Some parts of the Southeast are sill capturing over 90 moths per week, but in other regions captures dropped enough to shift to a four-day schedule. Maintain a regular spray schedule from first silk through 3-5 days before harvest. Rotate materials if possible. Despite high daytime temperatures this week, nighttime temperatures have dipped into the mid to low 60’s and daily average temperatures have declined from mid-70’s last week to about 70 degrees F this week. Low night temperatures mean slower rates of egg laying at night and slower hatch rate for egg masses. Drier conditions mean it is easier to maintain a regular schedule with good coverage. European corn borer counts remain high, especially in the Connecticut Valley. Watch for high infestations at the pretassel stage. With high flights we will also see plenty of ECB larvae entering ears through the tip during the silking period. They may move in as small larvae at any time during the silking period. These borers can take you by surprise if you are expecting that ECB will always show up in the tassel frits. However, the spray schedule for corn earworm should control these ECB as well.

8/07/03

TOMATO: TOM-CAST UPDATE

Tomato quality is good, and fruit is ripening. Leaf wetness periods have been seemingly endless this week – logging 13-24 hours at a stretch at our weather datalogger at South Deerfield. Nights have also been warm, resulting in temperatures ranging from 62-76 degrees F during the leaf wetness period. As a result, we’ve been logging daily DSV’s of 3 this week. It’s time to be on a fungicide schedule of not more than 7 days. Growers with large plantings of tomatoes may also be battling bacterial canker, which tends to hit larger acreage more heavily. In that case, you are probably already on a weekly application of copper along with fungicides.

8/07/03

BRASSICAS: FLEA BEETLE AND CATERPILLAR UPDATE
--Caryn Andersen, R. Hazzard

Flea beetle populations are again high on field brassicas. At the University of Massachusetts agronomy farm, flea beetles are feeding heavily on a wide range of brassica crops, from older cabbages and collards to newly-planted turnips and Asian brassicas. The flea beetles currently feeding are the offspring of the adult beetles that were present on crops in the spring. During warm weather, it takes one to one and a half months for beetles to progress from egg to adult (longer in the cool spring weather). Weekly dissections of field-collected flea beetles indicate that the females are still laying eggs, which means that new beetles will be emerging from now through September. Results from our spring field trials of pesticides indicate that, while row cover is the most effective method of reducing damage, both spinosad (in either Entrust or Spintor 2SC formulations) and carbaryl (Sevin XLR Plus) significantly reduce damage when applied as weekly foliar sprays. Join us at the South Deerfield Field Day for more details on current research on this pest.
A new generation of imported cabbageworms are hatching out, diamondback moth is going strong. Cabbage looper is present in the Connecticut Valley, which probably means it can also be found in other parts of the state. Keep a close eye on brassicas – especially underneath the leaves. Diamondback moths were found in a hoop house with mesclun greens in southeastern MA. These are not the preferred host, but they were causing small round holes in the leaves.

8/07/03

PEPPERS

Pepper harvest is underway in some fields, but many growers are still waiting for fruit to size up and reach maturity. Fruit set is generally good. European corn borer captures rose sharply this week and numbers are above the threshold of 7 moths per week at nearly all locations. It typically takes two weeks from the onset of flight before pepper fruit is attacked by borers. Insecticide applications should begin one week after the onset of flight, which means this week in some locations and next week in others (see charts of ECB captures in this and last week’s messages or check your own traps).
Insecticides for ECB should be applied at regular intervals during the second-generation flight period, especially in the next 3-4 weeks during peak flight when flights are well above the 7 moth/week threshold. The recommended interval depends on the material used. Acephate (Orthene , 7dh), methoxyfenozide (Intrepid 2F, 1 dh). or tebufenozid (Confirm 2F,7dh) can be applied at 10-14 day intervals; spinosad (SpinTor,1 dh) or permethrin (Pounce, Ambush, 3 dh), at weekly intervals, 2nd-generation pyrethroids (Capture, Baythroid, Warrior, Mustang, 5-7 dh),) may work as a slightly longer interval (7-10 days) and Bt products (0 dh) should be sprayed twice weekly.
Permethrin products will cause aphid outbreaks by destroying beneficials which keep aphids in check. Orthene provides good aphid control. Spinosad, while not having activity against aphids, has the advantage of conserving beneficial insects such as ladybeetles, which can reduce resurgence of aphids in crops such as peppers and sweet corn. The one-day pre-harvest interval and four-hour re-entry interval makes it particularly useful in peppers where harvest periods coincide with heavy pest pressure and the need for regular sprays.
Scout for green peach aphids by checking 4 leaves per plant on 25 plants. Natural enemies generally keep aphids under control. If numbers exceed an average of 10 aphids per leaf, controls are needed to prevent an outbreak that could impact plant growth and cover fruit with honeydew and sooty mold. Insecticides with good efficacy against aphids include Orthene, Provado (0 DH), Dimethoate, Horticultural oil, insecticidal soap, Metasystox-R. Of these, only Orthene also controls ECB.
We are seeing bacterial leaf spot in some fields (including in some resistant varieties). Hot, moist conditions favor bacterial leaf spot infections, so scout for this disease and apply copper products if it is present. Messenger may also help plants resist the disease.
Pepper maggot fly, is still active and more oviposition stings were found this week, compared to previous weeks, on cherry and bell pepper fruit in scouted field in southeastern Mass. If this is a problem on your farm, use one or two sprays about 10 days apart during this peak period of oviposition, to reduce adult activity.

8/07/03

PHYTOPHTHORA WATCH IN PEPPERS AND VINE CROPS…AND OTHER DISEASES OF VINE CROPS
--R. Hazzard, adapted from M. Hausbeck (Michigan State), R. Wick (UMass), M. McGrath(Cornell University)

Conditions have been favorable for Phytophthora capsici and growers should be on the alert and checking their fields regularly –especially fields with a history of this disease. Look for soft rotted tissue anywhere on the plant, particularly the stem and crown near the soil surface or any fruit. Search low-lying areas of the field first. Recognizing disease due to Phytophthora capsici is not always easy; often the only visible symptom of infection, especially for cucumber or tomato plants, is stunting. Because the disease often occurs in low areas of a field where water accumulates, many growers assume that the stunting is due to ‘water logging’ of the roots. Squash or pepper plants may have more obvious symptoms, with plants permanently wilted or collapsed prior to dying. Infected plants often have brown to black discolored roots and crowns. Disease is most obvious on infected fruit, initially as dark, water-soaked lesions which may develop a distinctive white ‘powdered sugar’ layer of spores on the surface of the fruit. Fruit infection is especially troublesome because the infection may occur days before the symptoms become visible. Use the Disease Diagnostic Lab (413-545-1045) to confirm any suspected outbreaks. Two diseases which can be confused with Phtophthora fruit rot are Pythium fruit rot, which is characterized by white fluffy growth like fine cotton, and Sclerotinia white mold, which has dense cottony growth with black, hard, pea-like structures imbedded in it.
Spread can occur with moving water in the soil, on any soil left on equipment used for tillage or harvest, or with windblown spores moving through the air. Phytophthora capscisi grows best at 80ºF, and can rapidly spread throughout a field under warm, wet conditions. The fungus produces lemon-shaped spores called sporangia on the surface of roots, crowns, and fruit of infected plants. Sporangia may be dislodged from infected plants by irrigation water, drainage water, or windblown rain. In water, sporangia release many smaller swimming spores called zoospores. Swimming zoospores are attracted by root exudates from host crops. One zoospore is all that is needed to infect a plant. Sporangia may also directly germinate and cause infection. Disease occurrence within fields often follows drainage patterns, but windblown rain may allow Phytophthora to spread across an entire field.
Production practices that can help prevent outbreaks:
Minimize puddling, whether from irrigation (fix leaks in irrigation systems!) or rainfall. Subsoil, clear pathways for drainage at the end of rows, etc. Irrigate conservatively, especially as fruit load increases in the field. If an outbreak occurs, plow under the infected patch including healthy plants that border the diseased areas. Remove diseased fruit from the field, but never dump culls or disease fruit from other fields or farms into production fields. If Phytophthora capsicii is introduced, it may remain indefinitely. Clean equipment that has been used in an infected field by washing with a strong water stream or power washer. Fungicides have provided minimal control in efficacy trials in New York State and elsewhere in the US in vine crops and should not be used alone without cultural practices. In pepper or cucumber, directed sprays of mefonaxam (Ridomil), copper or chlorothalonil may be useful as a preventative program.
Angular leaf spot is showing up in some fields. The symptoms of this bacterial disease are leaf spots (round at first, growing until they are limited by the leaf veins and become angular spots). Initially they look water-soaked or brown, then the tissue becomes translucent and dead, or may fall out as the leaf ages or grows. This disease attacks cucumbers, squash, and watermelon. Warm, humid conditions are favorable for this disease. Generally, this disease has not significantly affected yields in New England. If you think you have a significant amount of angular leaf spot, or it appears to be spreading, then copper applications may be warranted. It is not certain that copper applications are effective in preventing spread of the disease. If you do apply copper, use a boom sprayer. Do NOT use an airblast sprayer, which spreads the bacteria throughout the field. When using copper products -- especially with young vine crops -- avoid higher than label rates and wait for cooler temperatures if possible, as high rates at high temperatures have some risk of phytotoxicity. One caution is that symptoms of bacterial leaf spot of cucurbits (Xanthomonas campestritris pv cucurbitae) are very similar but can result in fruit rot, while angular leaf spot does not. Consult the Disease Diagnostic Lab for assistance in diagnosis.
Belly rot, caused by Rhizoctonia solani, has been reported in cucumbers. This begins on the underside of the fruit, where fruit is in direct contact with infected soil. It is most common in cucumbers but can infect other cucurbits. Water-soaked, tan- to brown lesions become sunken and cratered as they enlarge. Temperature is more critical than moisture for disease development, although high humidity under a thick foliage promotes disease. The optimum temperature is 81ºF. Mulch or other barrier between soil and fruit reduces disease.
Powdery mildew is being found in butternut and pumpkin fields, often still at rather low levels. However, we recommend that the first symptoms seen trigger a regular spray program (see July 24 issue for details).

7/08/03

TOMATO AND POTATO GROWERS SHOULD LOOK OUT FOR LATE BLIGHT
Adapted by R Hazzard from R. Wick

Bury cull piles. It looks like we are beginning to have a perfect late blight kind of year. Cool, wet conditions favor late blight (LB). With that in mind, it’s a good idea to get rid of any potato cull piles. Late blight can be carried over in cull piles and in volunteer potatoes. It can be carried over from the previous year or unsprayed potato plants will be more susceptible. Bury the pile with at least 2 feet of soil or cover with a black plastic tarp.

Late blight, caused by Phytophthora infestans, is much more destructive to potatoes and tomatoes than early blight. The fungus Alternaria solani causes early blight. Early blight can be expected to occur every year on tomato, and occasionally on potato. Conventional fungicide programs do a reasonably good job in managing early blight. On the other hand, late blight moves in very quickly and is very destructive during rainy weather when temperatures are between 65° and 70° F.
The temperature range for disease is wide, but is less destructive at the extremes. The late blight fungus is inactive above 85° F. Late blight has occurred occasionally in Massachusetts over the past five years. In a few cases, entire fields of tomato and potato were lost.
If you think you may have late blight, bring specimens to Rob Wick in the
UMass Disease Diagnostic Lab, Fernald Hall, UMass, Amherst 01003.
Call ahead for confirmation (413-545-1045, email rwick@pltpath.umass.edu).
Overnight mail can be sent from anywhere in the state.

6/12/03

POTATO: BE READY FOR COLORADO POTATO BEETLE EGG HATCH

Colorado Potato Beetle Egg Mass Missing eggs were eaten by an egg predator, the 12-spotted ladybeetle. Photo: Ruth Hazzard

Colorado potato beetles (CPB) are moving into potato fields and laying eggs. Walk your fields and look for CPB adults and eggs. Except for field edges in non-rotated fields, adult beetles do not usually cause enough damage to early potatoes to require control. The economic threshold for adult beetles in potato is 1 beetle per 2 plants (or per 2 stalks, in midseason).
Scouting. Look on the undersides of leaves for the orange-yellow egg masses. The fresher the eggs, the brighter orange the eggs will appear. If eggs have been around for a while, they appear a darker, brownish orange. One way to know when eggs first hatch is to flag the first ten egg masses that you see with bright surveyor’s tape or flags, and then check them every couple of days. This will tell you when the earliest eggs are hatching. New eggs will continue to be laid for the next 2-3 weeks.
Timing and thresholds. If you are using Bt’s, you want to apply the Bt when 20-30% of the eggs have hatched. If you are using spinosad (Spintor 2SC) or a broad-spectrum insecticide, you can wait till more larvae are hatched, until the oldest larvae reach the beginning of the fourth stage, when they are about 1/3 inch long. Applications made at this time with Spintor, Provado, AgriMek, or synthetic pyrethroids will kill all the larvae that have hatched up to this point. The threshold for small larvae is 4 per plant; for large larvae, 1.5 per plant (or per stalk in midseason), based on a count of 50 plants or stalks.
With cool conditions, beetle invasion of fields, egg deposition and then hatch can be spread out over a long period of time. This situation is not good as then you can have various stages of larvae as well as adults in your field. Or, if it warms up suddenly, you will have a rapid flush of larval hatch and feeding damage that may seem to explode out of nowhere. Hatched larvae go through four stages instars before they become adults. As the larvae get bigger, they do more feeding. The fourth, or largest, stage does 85% of the feeding damage.

Colorado potato beetle larvae just after hatch. This is ideal stage for using Bt. Killing larvae at any stage before the 4th istar prevents most of the feeding damage to leaves. Photo: Ruth Hazzard

Colorado potato beetles rapidly develop resistance to insecticides. This happens on a field-by-field basis, which means that you have control over how resistant “your” beetles become to any given product. Management strategies for CPB should use crop rotation and alternate classes of insecticides in each generation of the beetle. Admire resistance has developed to high levels in some fields in the Connecticut Valley where it has been used in successive years. In the summer of 2000, Mitchell Baker at UMass collected beetle eggs from 26 Connecticut Valley potato fields. Larvae were treated with a range of concentrations of imidacloprid to find out how susceptible they were to Admire. Dr. Baker found that there was a 25-fold range in resistance, that is, it took 25 times as much Admire/Provado to kill the larvae from the most resistant field compared to those from the least resistant field. There was wide variation among even neighboring fields, suggesting that the treatments that each individual field receives makes a difference in how much resistance develops.
To prevent resistance, alternate among classes of insecticides in each generation, and throughout the season. Classes include neo-nicotinoid systemics for furrow (Admire, Platinum) or foliar (Provado) application, synthetic pyrethroids (Asana XL, Baythroid, Ambush), carbamates (Thionex, Vydate), spinosad (Spintor, Entrust), Bt (Novodor FC), mineral (Kyocide), insect growth regulator (Agri-Mek). Wherever possible, do not repeat the same class in a single generation of the beetle. If you used Admire at planting, do not use foliar applications of Provado. Alternate applications of all synthetic pyrethroids with Provado, or with Spintor, or with a Bt. One strategy using all ‘biorationals’ would be to use spinosad which controls adults and all larval stages for the first spray, followed by a Bt to kill emerging young larvae. Fortunately, there are very effective alternatives to the highly toxic materials that were heavily used 15-20 years ago.
Here are three ‘biorational’ products – that is, they are quite safe to handle (“CAUTION” label) and easy on natural enemies, which help to keep aphids and CPB in check.
Spinosad (SpinTor 2SC, Entrust) gives excellent control of all stages of CPB at the 3.5 to 4.5 fl oz rate of Spintor or 1 to 1.5 oz/acre Entrust. For a heavy population, two applications about 10 days apart, with the initial application when third instars occur, will control the first generation. Spintor has the advantage that it will control both adult and larval CPB, including large larvae. European corn borer, which can cause tunneling damage in stalks, will also be controlled. Entrust is a wettable powder formulation that is allowed by the National Organic Program for use in certified organic crops.
Abamectin (AgriMek 0.15EC) is mainly a contact material, which controls larvae. It may be best used early in the season, when good coverage is easier to obtain. Rates of 5-6 fl oz rate per acre gave effective control in commercial fields in trials on Long Island. The lowest labeled rate is 8 fl oz. Bt tenbrionis
(Novodor FC) controls small larvae, through the third instar. Time applications to begin when 30 percent of the eggs have hatched. Where fields are densely populated and eggs are hatching continuously, reapply every 5 to 7 days. According to our most recent information, Novodor and other formerly available Bt products (eg, M-Trak, Beetle Beater) are no longer approved for organic producers.
Check with the MIC (Massachusetts Independent Certification, Don Franczyk
(978)297-4171
dfranczyk@starpower.net

6/2/02

STRIPED CUCUMBER BEETLE PART TWO
Ruth Hazzard

Striped cucumber beetles are becoming active and numbers are likely to jump rapidly this week. Direct-seeded pumpkin, winter squash, melons and cucumbers that are just emerging, as well as transplants that are still young are highly susceptible to both feeding damage and transmission of bacterial wilt, which is vectored by the cucumber beetle. The cotyledon up to the five-leaf stage is most susceptible.
Beetles are very mobile and can build up rapidly, so fields should be scouted at least twice a week. Activity tends to be high during hot sunny weather – so this week may bring them out. Rotation makes a difference! Numbers will be higher and infestation earlier in non-rotated fields.

Scouting: Look for signs of feeding on the underside of leaves, especially the cotyledons. Beetles are often found underneath leaves or in cracks in the soil. Check sets of 5 plants in at least five areas of the field (25 plants total), counting number of beetles on or near the plant. This can be done in about 15-20 minutes. Check field edges for hot spots. Beetles often colonize from field edges and numbers will be higher in the first rows near a woods or fallow area. Border treatments or border trap crops may help reduce infestation of the whole field. See the 2002-2003 New England Vegetable Management Guide for specific materials. (Don’t have one? Call 413-545-2717 to order your copy).

When to spray? Controlling cucumber beetles in the cotyledon to 5 leaf stage is the only way to preventing bacterial wilt. For susceptible crops such as cucumber, summer squash and zucchini, muskmelon, gourds, and some winter squashes and pumpkins, lower thresholds are needed. Do not allow numbers to exceed 1 beetle per two plants. The time between first arrival of beetles and that threshold can be short, so keep an eye on fields once you see any beetles and spray within 24 hours of reaching threshold.

Organic Controls: For organic growers, kaolin (Surround WP) provides a new option. Other organic options are row cover, pyrethrin (Pyganic Crop Spray 5.0 EC), perimeter trap crops (see below). Available Rotenone products have lost approval under the National Organic Program. For growers using Surround, here are some suggestions:

• Apply before beetles arrive. This acts as a repellent and anti-feedent so must be present before damage is done.
• If you are using transplants, apply before setting them out. This saves time and materials.
• With direct-seeded crops, apply as soon as seedlings emerge if beetles are active.
• Ensure good coverage of the foliage (it will look like it was sprayed with white latex paint), including, if possible, the undersides of leaves (not easy when cotyledons are close to the ground).
• Reapply after a heavy rain.
• When mixing, add the powder to water and allow it to settle slowly. Once the powder is fully wet, agitate gently. This reduces clumping. One approach is to mix a more concentrated slurry in a bucket and then add the slurry to the tank, as the dry powder could cake if added directly to the tank mix.
• Continuous agitation is needed.
• Although kaolin is safe in terms of skin exposure or ingestion, handlers should take precautions to avoid breathing the powder. Wear a respirator or mask when mixing and spraying.

6/2/02

PERIMETER TRAP CROPPING FOR CUCUMBER BEETLE MANAGEMENT
Adapted from PTC for Yellow and Green Summer Squash and Perimeter Trap Cropping Works!, by T Jude Boucher and Robert Durgy, University of Connecticut Cooperative Extension System.

Trap crops are used to protect the main cash crop from a pest or complex of pests. The trap crop can be a different plant species, variety, or just a different growth stage of the same species as the main crop, as long as it is more attractive to the pests when they are present. Perimeter Trap Cropping involves planting the attractive plant species so that it completely encircles the main crop like fortress walls. A trap crop barrier on all sides is useful when it is necessary to protect the crop from a pest attack that may come from several or unknown directions. This technique works best against pests that tend to damage the crop along the edge of the field (at least initially) – such as striped cucumber beetle. Perimeter Trap Cropping functions by concentrating and/or killing the pest in the border area, while reducing pest numbers and disease spread on the unsprayed cash crop in the center and by preserving natural enemies. Perimeter Trap Cropping often eliminates the use of broad-spectrum pesticides on the cash crop, which helps preserve natural enemies and helps prevent resurgence of the primary pest population, secondary pest outbreaks and additional spraying to solve these “man-made” problems. Perimeter Trap Cropping often results in improved crop quality and dramatic pesticide savings. Less spraying usually translates into lower costs.

Blue Hubbard around yellow summer squash. In 2002, Connecticut researchers attempted to stop cucumber beetles and squash vine borers damage on summer squash using Blue Hubbard as a perimeter trap crop. Blue Hubbard was chosen because it is highly attractive to beetles, grows fast, and is not susceptible to bacterial wilt so it does not serve as a reservoir of wilt for the rest of the field. In the 2002 trials, over 94% of the cucumber beetles in the experiment were on plants in the perimeter. Beetle populations on the unsprayed main crop in the center were reduced by up to 95%. In addition, spraying the perimeter trap crop reduced squash vine borer infestation on the unsprayed summer squash within by 88%. Six commercial cucurbit growers successfully employed the technique in 2002. All the growers improved their pest control and reduced crop damage using Perimeter Trap Cropping, and all said they would continue to use trap crops in the future.

How to use perimeter trap cropping in yellow and green summer squash – or other vine crops. A number of growers in CT and MA are testing Perimeter Trap Cropping in summer squash and butternut this season. You may be interested in trying it, or come to summer twilight meetings to learn more about it. Here are some suggestions if you want to try it:

• Use a rotated field where cucumber beetle populations are not extremely high.
• Plant the trap crop earlier or at the same time as the main crop.
• Use the same in-row and between row spacing to plant the main crop and the perimeter trap crop row (or rows) of Blue Hubbard. Plant the outside rows along the length of the block by machine. Trap crop plants at the end of each row can be placed by hand or by machine (drive across the rows). Don’t worry if all the Blue Hubbard plants don’t line up with the main crop rows or are killed between rows by tractor tires. As long as most of the border plants survive on all sides of the field, without major gaps (>15 ft), the barrier should still function.
• Scout the trap crop at least twice weekly and spray the border with an effective insecticide (Asana, Sevin for conventional, Pyganic for organic) as soon as beetles are found. Don’t wait for beetles to build up in the borders. It is important to maintain healthy border plants and to prevent redistribution throughout the field. However, even without border sprays, PTC reduces beetles in the main crop. Scout again to determine if repeat sprays are needed in the border. 103 sprays may be needed as beetles continue to colonize.
• Don’t mix another, highly attractive vine crop inside the border. Or, if you do, monitor it closely to determine if sprays are needed on that main crop. For example, zucchini is more attractive than summer squash and may need to be sprayed even if it is inside a blue hubbard perimeter.
• Where heavy infestations might be expected, such as borders along woods where beetles may have overwinter, use a wider perimeter of 2-3 rows.
• Watch for more details on twilight meetings at demonstration farms in Connecticut and Mass!
PTC can also be used to reduce pepper maggot infestations in pepper – with a ring of cherry peppers around bell peppers - and diamondback moth in cabbage – using collards as the trap crop. For more information visit the UConn website at:
http://www.hort.uconn.edu/ipm/veg/htms/trpcrops.htm.

6/2/02

INSECT CONTROL FOR EARLY SEASON ROW COVER SWEET CORN
John Mishanec, Area Vegetable IPM Educator, Cornell Cooperative Extension, Capital Vegetable News, Vol. 5:1-- Spring 2003

A common technique in cold climates to speed maturity in sweet corn is to start the corn under plastic or floating row cover. Once the corn is from one to two feet tall, the plastic or row cover is removed. Because it is so much farther advanced than sweet corn planted on bare ground, the crop attracts early season European corn borer (ECB). Scouting for insect damage is difficult or impossible because the larvae are deep in the plant. Working with two large-scale growers of row cover sweet corn, a successful technique for insect control has been identified. Pheromone traps next to the fields are used to monitor early season corn borer flight patterns.
Three years of informal observation and one year of data collection have confirmed the results. Growers have developed confidence in using the technique and have achieved both high quality early sweet corn and minimal pesticide application. Remember, this technique only works on row cover or plastic corn in early season. For bare ground sweet corn, you should go out and scout the fields while in whorl and make your spray decisions based on insect feeding levels. In early June, we will have more information on scouting techniques in this newsletter.

Growers wishing to purchase their own traps can obtain the “Scentry Heliothis Trap” from Great Lakes IPM Inc. 10220 Church Road NE Vestaburg, MI 48891 Ph 1-800-235-0285. The traps cost $48.00. You will also need lures. The “Trece” European corn borer II (NY) lure is sold in packages of 25 and cost $44.00. Lures should be changed every two weeks. The traps are good for about 10 years if you don’t leave them out over winter. Gempler can also supply traps but they are a little more expensive. Put the trap out the last week of May next to your row cover field. Monitor the traps every 3-4 days. You will catch a few of the tan ECB moths regularly until a point when the counts jump from a couple to maybe 10 or 15 moths. This is the time to start thinking about applying an insecticide application in 3 to 4 days. The moths are attracted to the row cover corn first because it is the most advanced. You want to wait a few days before applying an insecticide to give the eggs time to hatch. The goal is to catch the immature larvae on the outside of the plant before they dig deep into the corn. After you have put on an application, wait 3-5 days and apply a second application.

Once the early corn is harvested, you can move the traps to other sweet corn fields and monitor for the second flight. Remember to keep changing the lure every two weeks.

CORN EARWORM TRAPPING NETWORK
Rich Bonanno, Vegetable Extension Weed Specialist, Dept of Plant and Soil Sciences, UMass Amherst

The network of pheromone traps that is maintained around the state --and the region-- depends on growers as well as private IPM consultants, USDA agency staff, and UMass Extension. We report those trap counts here and on the Northeast Pest Watch website. The growers that are part of this network check their traps once or twice a week and send in the numbers -- by phone, email or FAX. Each year the system gains more growers who are willing to take the time and contribute to an expanding, self-sustaining network of information. If you would like to be part of this network, please contact us. We will provide lures to growers in the network.

Weed Management Advice
Frequent rains have activated most herbicides that have already been applied. If rains become more infrequent, irrigation may be required to activate any herbicides that are not incorporated. This may seem odd since most soils are wet; however, additional moisture will still be needed to move the herbicides off the soil surface. Soil temperatures have been cool and weeds are not germinating as quickly this spring. This may allow herbicide applications, especially in corn, to be delayed a bit to coincide with additional rainfall. For anyone using stale beds, weed germination will be slow and extra time will likely be required to get good weed emergence.

5/19/03

CUCURBITS: PREVENTING PHYTOPHTHORA BLIGHT
R. Hazzard, adapted from M.T. McGrath, Dept of Plant Pathology, Long Island Horticultural Research & Extension Center, Cornell University

Most of our winter squash and pumpkin crops will be seeded in the next couple of weeks. Last year’s dry conditions gave most growers a break from Phytophthora blight, but in the previous years many fields were heavily infected with Phytophthora and growers remember all too clearly losing all or part of a crop to this disease. The only way to manage this disease is through an integrated approach – and cultural practices are the major line of defense. Prevention is very important because Phytophthora blight is very difficult to suppress once it starts to develop in a field. After it has occurred on a farm it is difficult to continue growing susceptible crops without Phytophthora blight reoccurring.

Infections occur when the following conditions are present:

1. A susceptible crop (cucurbits, peppers, tomatoes, or eggplant) growing in the field

2. Soil infected with Phytophthora spores,

3. Standing water (fully saturated soil).

Low-lying areas are sites where a Phytophthora outbreak could begin. We know that many soils around the state are infected with Phytophthora spores from outbreaks in past years. These resting spores (oospores) are most likely to germinate when there are alternating periods of dry soil followed by saturation. Standing water (or fully saturated soil) and warm temperatures are ideal conditions for spores (both oospores and sporangia) to germinate and release the swimming zoospores. These mobile spores will travel through the soil water, in surface water, in splashing water, or aerially in windblown rain to infect leaves, roots, crowns, or fruit. Once established, the fungus produces a yeast-like growth that contains many sporangia. Sporangia are lemon-shaped structures that cause new infections as they disperse into the rest of the field.

The following list of recommendations was developed by Margaret McGrath (Cornell University) and adapted for Massachusetts. These reminders may help you decide where and how to plant, and help prevent problems later in the season. The key goals are to manage soil moisture to avoid saturated conditions that allow the disease to get started, and to avoid introducing the pathogen to new fields.

1. Select fields where Phytophthora blight has never occurred when possible. The fungus that affects cucurbits also causes blight in pepper, fruit rot in eggplant, and buckeye rot in tomato. An effective rotational period has not been identified yet. Two years has been shown to be insufficient, therefore select a field where susceptible crops have not been grown for at least 3 years. Both mating types of the pathogen have been found in fields in New York, and also in other states. Therefore it is possible for the pathogen to produce oospores, which are capable of long-term survival. Rotation will be more successful where only one mating type occurs. Selected fields should be isolated from fields where Phytophthora blight has occurred to avoid the potential of the fungus being moved (in run-off or on farm equipment) from the infested field into the cucurbit crop. Late blight of potato and tomato is caused by a different fungus (P. infestans); therefore, previous occurrence of late blight is not a concern in field selection.

2. Select well-drained fields.

3. Make sure water will be able to drain out of the field. If water does not normally drain out of the field, then make a trench between beds or rows at their ends, make a ditch or waterway across the end of the field for water coming out of the field in the trenches, and continually grade soil at the end to allow water to leave.

4. Physically separate plantings of susceptible crops (cucurbits, pepper, eggplant, and tomato). Plantings should be located such that there is no opportunity for water to move from one planting to another. The pathogen can also be dispersed in rain splash during storms. Therefore it is prudent to consider prevailing wind direction when deciding where to locate multiple plantings of susceptible crops on a farm.

5. Minimize hardpans and plowpans by subsoiling or chisel plowing before planting, and by not driving through wet fields.

6. Do not plant the crop in areas of the field that do not drain well. Plant a cover crop in place of the crop in these areas. It is worth sacrificing a small area that will never be harvested to avoid the risk of losing the entire crop.

7. Prepare raised dome-shaped beds for summer squash and other bush-type crops. Use a bed shaper to provide more lasting beds as opposed to a simple ridge. Use a transplanter that doesn’t leave a depression around the base of the plant. Fill in any depressions.

8. Clean farm equipment, shoes, etc. of soil between fields. Movement in soil on equipment and shoes probably is an important means by which Phytophthora has been spread between fields on farms and may account for the occurrence of Phytophthora blight in fields with no previous history of susceptible crops.

9. Subsoil between rows after planting and before vining to improve drainage. Subsoil again as needed after rain. Good drainage is also important for driveways in fields, as symptoms have been observed first on plants next to the compacted soil of driveways, therefore, subsoiling along the edge of driveways is also needed. It is preferable to plan driveways before seeding leaving ample space, instead of seeding the entire field and then driving over plants.

10. Avoid over irrigating and fix leaks in the irrigation system that cause puddling in certain areas of the field. Normal irrigation practices usually do not encourage Phytophthora blight except when leaks frequently occur. Do not irrigate at night time when temperatures are above 70°F.

11. Select resistant varieties if possible. When growing small-fruited pumpkins, select varieties producing hard, gourd-like rinds (such as Lil’ Ironsides). These have been shown to be substantially less susceptible than varieties with conventional rinds. In peppers, use a Phytophthora resistant variety such as Paladin.

3/27/03

FUNGICIDE UPDATE FOR VEGETABLES 2003
Robert L. Wick, Department of Microbiology, UMass, Amherst

STROBILURINS: These are a new class of fungicides that have a relatively broad spectrum of activity. Strobilurins would be a good choice for Early Blight. Late Blight and Powdery Mildew are on several of the labels. Some are excellent for Powdery Mildew. Resistance development is a problem. If you use strobilurins, make sure you rotate with chemicals outside of this class.

NEW FUNGICIDE PRODUCTS

NOVEL CHEMISTRY/BIOLOGICALS:
Actigard, common name: acibenzolar-s-methyl, is a synthetic analogue of salicylic acid (active ingredient of aspirin). It is not toxic to microorganisms but it causes an induction of resistance in the plant. Currently the label is very short but it does include Bacterial Spot and Speck of tomato, and Downy Mildew and White Rust of spinach. Possibly result in reduced yield in tomato and yellowing in spinach.
Contans WG, a fungal biological control agent, Coniothyrium minitans. For control of Sclerotinia sclerotiorum (Sclerotinia Blight).
Messenger, common name: harpin. Like Actigard, Messenger stimulates defense mechanisms in plants. Messenger is a protein produced by a bacterium. There are a number of vegetable crops on the label. In addition to disease control the product is supposed to increase yield.
Serenade is the trade name for a formulation of the bacterium Bacillus subtilis. Serenade has several vegetables on the label but has a short list of diseases (Powdery Mildew, Downy Mildew, Bacterial Spot of tomato).
Sonata, Bacillus pumilus, is produced by the same company that makes Serenade. Similar spectrum of activity.
T-22 is a formulated product of the fungus Trichoderma harzianum. Trichoderma is a common soil-inhabiting fungus that is relatively antagonistic toward plant pathogens. In addition to vegetables, it has herbs on the label. It is compatible with a number of common fungicides. T-22 is for the control of root diseases.

Fungicide Resistance Management in Vegetable Crops: (for both old and new materials) Fungicide selection is important. Above all, you must know what pathogen you are trying to control. Next, you must select a material that will adequately control the pathogen. If you anticipate making several applications of a fungicide that may result in pathogen resistance, you should have
one or two appropriate fungicides to rotate with. The following table of fungicides tends to result in resistance.
Avoid applying them twice in a row. You can rotate from class to class but do not rotate within the same class.


FUNGICIDES WITH HIGH RESISTANCE POTENTIAL

*earlier formulations of Ridomil (metalaxyl) are chemically related to mefenoxam and should not be rotated with each other.
However, combination products such as Ridomil/Bravo do not tend to result in resistance.

The following fungicides do not tend to result in resistance. They make good rotational partners for the above fungicides.

FUNGICIDES WITHOUT RESISTANCE POTENTIAL

INSECT MANAGEMENT UPDATE FOR VEGETABLE & FRUIT CROPS 2002-2003
Celeste Welty, Extension Entomologist & Associate Professor OSU, Columbus

NEW PRODUCTS
Cruiser 5FS (thiamethoxam): Commercial seed treatment for sweet corn, for systemic control of corn flea beetle; made by
Syngenta, registered October 2002.
Entrust 80WP (spinosad; same as A.I. as in SpinTor): New formulation that meets requirements of national organic program;
made by Dow AgroSciences, registered August 2002.
Assail (acetamiprid), a neonicotinoid from Aventis/Bayer/Cerexagri: 70WP registered March 2002 for apple and pear to control
aphids, leafminer, leafhoppers, codling moth, and psylla; and for tomato, pepper, eggplant, leafy veg., cole crops, collards, kale and mustard greens for aphid, whitefly, Colorado potato beetle control; 70WSP for grapes for leafhopper control (May 2002).
Acramite 50WS (bifenazate): For spider mite control on apple, pear, plum, peach, grape and strawberry; made by Uniroyal/
Crompton, registered February 2002.
Courier Insect Growth Regulator 70WP (buprofezin): For use on lettuce, tomato, cucumber, melons, pumpkins and squash to
control immature whiteflies; & Applaude 70WP Insect growth Regulator (buprofenzin): For use on grapes to control leafhopper nymphs, also whiteflies, mealybugs, scales; made by Nichino America, registered January 2002.

REGISTRATION EXPANDED TO ADDITIONAL CROPS
Warrior T (lambda-cyhalothrin). Label expanded to include beans, peas, peppers, and eggplant.; expanded January 2003.
Esteem 35WP (pyriproxyfen): An insect growth regulator made by Valent, for scale and caterpillar control, new for stone fruit;
registered November 2002.
Intrepid 2F (methoxyfenozide): An insect growth regulator made by Dow, for caterpillar control, new for grapes, sweet corn,
pepper, tomato, eggplant, cole crops, greens, leaf lettuce & other leafy veg; registered on supplemental labels, September 2002. An improved version of Confirm (tebufenozide) registered since 1999 for cole crops, pepper, tomato and eggplant.
SpinTor 2SC (spinosad): New for brambles, grapes, radish, turnip, carrot and herbs (Sept. 2002); blueberries, beets (Jan. 2002);
strawberries (Sept 2001); asparagus (July 2001); for control of caterpillars, dipteran leafminers, thrips, asparagus beetle; made by Dow.
Baythroid 2EC (cyfluthrin): A pyrethoid made by Bayer; new for cole crops, mustard greens, leaf and head lettuce, dry and
southern peas; registered September 2002.
Avaunt 30DG (indoxacarb): For caterpillar control, new for Chinese cabbage (nappa), potato, eggplant; made by DuPont,
registered July 2002.
Capture 2EC (bifenthrin): A pyrethroid made by FMC; new for caneberries (raspberries) for caterpillar and root weevil control;
registered May 2002.
Fulfill 50WDG (pymetrozine): For aphid and whitefly control, new for cole crops, collards and other leafy brassica greens, leaf lettuce and other leafy vegetables, made by Syngenta, registered March 2002.
Mustang 1.5EW (zeta-cypermethrin): A pyrethroid made by FMC, for beetle and caterpillar control; new for tomato, pepper,
eggplant, beans and peas; registered January 2002.
Surround (kaolin): New for bean, pea, potato, beet, radish, cole crops, collards, mustard greens, lettuce and other leafy
vegetables; made by Englehard; registered March 2002. OMRI listed for organic farms.
Provado 1.6F & Admire 2F (imidacloprid): New for beans for aphid and whitefly control; made by Bayer; registered June 2001.
Agri-Mek 0.15 EC (abamectin): New for grapes for mite control; made by Syngenta, registered March 2001.

MODIFIED USES
Fulfill 50WDG (pymetrozine): Pre-harvest interval shortened from 14 days to 0 days for cucurbits, tomato, pepper and eggplant.

DISCONTINUED USES
Guthion (azinphosmethyl): Cancelled on beans, broccoli, cabbage, cauliflower, celery, cukes, eggplant, melons, onions, peppers,
spinach and tomatoes (Sept 2002).
Actara (thiamethoxam): To be cancelled on tomato, eggplant, cucurbits in USA; & apple in OH.
Di-Syston 15G (disulfoton): Cancelled on tomato; still ok for cole crops, pepper and potato.
Monitor (methamidophos): Cancelled on cole crops, now use only on potato and fresh tomato.

DISCONTINUED PRODUCTS
Methoxychlor: Tolerance revoked October 2002; products suspended from manufacture and sale since June 2000.