Hello MOFGA growers,

Here is the pest update for the early part of June, 1999. Remember, we have to thank the IPM program at the University of Massachussetts for a good part of the material here, and the IPM program here at UMO Extention too. Also, I want to remind you to please send me any information you have as to what pests and disease are pestering you now so I can pass the word around.

By the way, this message is being sent to all MOFGA certified growers with email addresses. The rest of the growers will have to get it off the web, either at home or their public library.

CROP CONDITIONS
Crop growth remains ahead of schedule, but the heat and strong sun of the past week have dried everything out again, and rain is needed. Early transplants are showing stress signs from transplanting and yellowing. The dry soil has little available N in it, the roots of the transplants are shocked by the move and in many cases do not cover enough area to support the top of the plant which has just been put into a harsh environment of lots of sun and wind. When you transplant be sure to provide water and a starter solution of compost tea if you can.

Transplanting of peppers and other warm-season crops, and seeding of pumpkin and butternut squash and succession crops like sweet corn, brassicas and lettuce, continues. Harvest of early lettuce and radishes is underway.

SUMMER COVER CROPS
This is not the usual time to be thinking about cover crops -- but it should be, any time of the year you have bare ground for an extended period of time. This could be land that you were not able to put a cover crop on last fall or land that might be coming out of production with spring crops like lettuce. If you do not plan on double cropping you should think about putting down a cover crop. Many growers are in the habit of leaving fallow land until September when they will seed it with winter rye. Seeding a cover crop now will produce lots of organic matter, add soil nitrogen (if you use a legume) and help to keep weeds from going to seed.

Here are some options:

Oat - This is a very useful cover crop for us in Massachusetts. Unlike winter rye, oat will grow very vigorously and straight up when seeded in the spring or summer. We frequently seed this cover crop during the summer months at the Research Farm in S. Deerfield on land that is not in production. It is readily available, but beware that you do not get oats that have been cooked (used for animal feed). Oat seeded this early will probably produce viable seed before frost. For this reason you might want to incorporate it (or simply mow it) before it goes to seed. Seeding rate - 100 lbs/acre.

Sorghum x sudangrass - As the name implies this cover crop is a cross between sudangrass and forage sorghum. Different companies use different trade names ('sudex' being one). One nice characteristic of this cover crop is that it produces a sterile seed so there is no concern of it re-seeding. This plant is frost sensitive, so it can be seeded any time now. If you have land that you are trying to 'build up' this is a good choice since it produces a tremendous amount of organic matter. When seeded in mid June it can get eight feet high by the fall. We did some work at the UMass Research Farm demonstrating that the addition of a small amount of nitrogen at planting can produce a much bigger plant. I would not apply more than 50 lbs/acre. Do not plant after July since it will die with a frost and not grow enough to justify the cost of the seed.

There has been some concern about how to manage sorghum x sundangrass in the fall. My experience with this cover crop was that it was not difficult to manage, however you may want to seed a little of it the first time in order to get some experience with it. It will die with a hard frost. You can either leave it till the following spring or incorporate it after a frost and seed rye. After a hard frost I let the plant residue dry down and then mowed it with a brush hog and then disked it in to seed winter rye Seeding rate - 40 - 50 lbs/acre.

Hairy Vetch - Hairy vetch is a cover crop that is being used by a lot of growers in the late summer and fall. This crop can also be planted in the spring and early summer and will do well. When vetch is seeded this early it will not usually survive the winter (whereas it will survive the winter when seeded in late August or September). The following spring the nitrogen from the dead vetch will become available, so this is when we want the cash crop in the ground to be able to take up the available nitrogen. It can be seeded alone or in combination with oat. Seeding rates: 25-30 lbs/acre (using a grain drill); 35-40 lbs/acre (broadcast); 40 lbs/acre of oat when seeded with vetch.

Buckwheat - This is another cover crop that growers will seed in the summer months. It is frost sensitive so it can be planted any time now. It is used by some growers to suppress weeds since it grows very quickly, however it will not add much organic matter. Be sure to mow or incorporate before it goes to seed. Seeding rates: 60 - 70 lbs/acre.

Soybeans - This is a crop that unlike most of the legume cover crops we think of is adapted to warm weather. If you need to fix a lot of nitrogen during the warm months soy beans may be for you. They are a summer annual that should be mowed and tilled in when they flower. They are easily crowded out by weeds so only use them in a field that you have fairly good control of already. They will grow on any soil, even sandy soils, with good drainage but do need moisture. They do not require a high lime content like alfalfa does. Seeding rates: 45-60 lbs/acre. Depth: 1 inch.

All of the cover crops mentioned above will perform much better if they are seeded with a grain drill. The grain drill we use in S. Deerfield is at least 50 years old (it was designed to be pulled by a horse!). It is extremely accurate and easy to use. I'm told that old grain drills like this one are easy to find at auctions around the area. Keep an eye out for them, they are well worth it.

--Frank Mangan, University of Mass (I added some and changed some to fit Maine)

RECENT PEST REPORTS AROUND MAINE
Flea beetles are still out in numbers all over the state. I have heard of total loss from the horse radish flea beetle, one of the many species. Cutworms are still a problem and in some areas, down east especially, very bad. Ticks have been reported in high numbers in the southern part of the state. The strawberry clipper damage is really showing up now but most of the damage is already done...you are just seeing the large number of clipped buds now. The threat of economic harm from this pest is very low at this time. Most of the flower buds are now beyond the bloom stage and the ones they can still get are the very tiny berries anyway. Tarnished plant bugs are very active. We are finding adults and lots of nymphs in most fields scouted. If you have control, do not mow any fields near sensitive crops now because it will drive the TPB. I have had reports of the first colorado potato beetle in the southern part of the state.

SWEET CORN: CROWS AND CORN BORERS
It looks like European corn borer emergence is beginning in Mass. Be ready.

The biggest losses in corn at this time of year are often from crows, which pull up seedlings and can decimate a field of young corn. Cost-effective, safe, and neighbor-friendly options for repelling crows and other birds have been limited, and we would like to make growers aware of a relatively new device that some growers are finding effective. This is a small rotating pyramid, with mirrors on three faces, that can be placed on the ground or on a platform. It is powered by a car or lawmmower battery. Several types of birds including crows, blackbirds are reported to be repelled by the moving, shiny surface. Geese are not. The pyramid may need to be moved every few days, as with other frightening devices. One advantage is that it is silent and will not disturb neighbors. However, it may be more effective when combined with recorded distress calls. We are seeking more research-based information on the device, so that we could make a more definitive recommendation about its effectiveness. Currently, we have grower reports that the device has been effective in reducing crow damage to young corn. It is named the "Peaceful Pyramid Birdscarer" and is manufactured in England. A local distributor is Fenant Farm Machinery, 545 West Hill Rd., Troy, NH 603-242-6417. I would be very interested in hearing from anyone who has purchased and used the device (call 413-545- 3696).

Other repelling devices include recordings of distress calls or predatory birds, visual deterrents such as scare-eyes or shiny tapes, and exploding devices such as shellcrackers and cannons. Often, birds are most effectively repelled by a combination of types of devices. Some sources of auditory and visual frightening devices are: Birdbusters, 300 Calvert Ave, Alexandria, VA 22301, phone (703) 299 8855 Bird-X, Inc, 300 Elizatbeth Ave., Chicago, Ill 60607 (800) 662- 5021 Gemplers' 100 Countryside Dr., PO box 270, Belleville, WI 53508 (800) 382-8473

Note: this list is definitely not exhaustive; inclusion in this list does not imply product endorsement nor does exclusion imply lack of endorsement. Other suppliers are invited to contact us.

--Ruth Hazzard, U Mass Extention

CRUCIFERS
The risk of new infestations from the first flight of cabbage root maggot is very low now. Unsprayed cabbage, broccoli, kale and collards that were scouted this week in the Connecticut Valley were virtually free of maggot eggs -- either none were found, or only one or two eggs per 40 plants. On untreated, older plants there were some maggots found, indicated that the early eggs have had time to hatch and begin feeding on roots. However, one grower reported that an untreated, early-planted field has yet to show any maggot damage, and it is possible that the hot, dry conditions of early to mid May brought soil surface temperatures high enough to kill maggot eggs. Eggs which are subjected to temperatures over 90 oF die. Dry soil under a strong sun can easily exceed 100 oF in the upper two inches. In addition, the membrane of the cabbage maggot egg is permeable, and is subject to dessication under dry environmental conditions. This lethal combination of heat and dryness is one reason why we rarely see maggot problems in mid-summer, even though there is a second flight during that period.

You can now take floating row covers off if you have not done so yet. Remember that these plants have not seen full sun yet, so it is best to remove covers on a cloudy day or in the evening.

CUCURBITS

Flea beetles are still out and if a major problem plants should be dusted with 5% rotenone. Mild infestations can be tolerated as the plants will out grow the beetles.

This is the time of the season when cucurbits are most susceptible to Striped Cucumber Beetle(Acalymma vittatum). I have had reports from the Alna area that they are out.

Direct seeded pumpkins, winter squash, melons and cucumbers are just emerging, or will be emerging within the next couple of weeks. Most transplants are still young. Feeding damage from the cotyledon up to the five leaf stage is most critical, because it can reduce yields if it is severe enough. 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. 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. To scout, check sets of 5 plants in at least five areas of the field(25 plants total), counting number of beetles per plant. Check field edges for concentrations or hot spots.

Adult beetles are about 1/5 inch long, yellow and black, with three longitudinal black stripes extending to the tip of the wing covers. They spend the winter in protected locations near last year's cucurbit fields, and feed on blossoms of many alternate hosts until cucurbits emerge in the field. Cucurbitacin, the bitter element in cucurbits, serves as an attractant and feeding stimulant, which helps beetles to find their host plants. There are crop and variety of differences in cucurbitacin levels and in feeding preferences by cucumber beetles. Beetle preferences for different crops and varieties were studied by Mike Hoffman at Cornell University in 1992 and 1995 Weekly samples were taken after tranplants were set out at the cotyldeon stage. The results show a wide range of preference. Though this obviously won't be useful in selecting varieities for this season, it may be of interest to note if some of your varieties are likely to be highly preferred or not.

Appendix Ranking of preferences by cucumber beetles recorded in field tests:

Pumpkins: 5 or more beetles per plant

Winter Squash: 2 or more beetles per plant

Both: more than 15% of the plants showing at least 20% defoliation from feeding injury.

BACTERIAL WILT.
A major concern with striped cucumber beetles is their ability to transmit bacterial wilt (Erwinian tracheiphila) to cucurbits. The bacteria overwinters inside the beetles and is transmitted during feeding. Beetles feeding on infected plants during the season also acquire the bacteria and can move it to other plants. Different studies (in Indiana and Pennsylvania) of beetles collected from cucurbits at the beginning of the season found initial rates of infection ranging from 1-8%. Beetles collected later in the season had highly variable infection rates, which tended to be higher than the early-season infection rates.

The bacteria multiply inside the water-conducting tissue of the plant (xylem), and are translocated throughout the plant. In 1-3 weeks of the infection the pathogen will begin to block the flow of water in the vascular tissue, which causes leaves and vines to wilt. The branch of the vine that is first infected wilts first and, as the bacteria spread, other branches wilt in succession.

Bacterial wilt can cause severe losses in cucumbers and muskmelons and growers should treat these crops with an appropriate insecticide at the first sign of beetles (see the New England Vegetable Management Guide for suggested materials). Floating row covers can protect the crop while they are in place, but they must be removed to allow for insect pollination.

Squash and pumpkins can be infected by bacterial wilt, but losses are rare. It is possible that some of the wilt symptoms that were observed in pumpkins in 1998 were the result of bacterial wilt, and UMass will be conducting a survey to assess whether this disease is present in winter squash or pumpkins throughout in Massachusetts. Until this is documented, on these crops our main concern is with feeding damage.

In the early stages of growth, insecticide use can be significantly reduced by only spraying the rows of plants and not the bare ground between them. This can be accomplished by using only the nozzles over the rows and shutting the others off. If the nozzles on your spray boom don't line up with the crop rows, consider building another boom to match the crop. Some growers have made several booms to match various row spacings. They use clamps so they can quickly attach and change booms as they spray crops with different row spacings. Growers with small to moderate acreage can use back-pack sprayers to treat the "hot spots".

Organic growers report good control with Pyrenone. When spraying for cucumber beetles spray very early in the morning when they are quite and don't fly away as you move up the row.

POTATO: LATE BLIGHT AND EARLY BLIGHT MANAGEMENT
There are two major diseases of potato in this region, late blight and early blight. It is important to understand that these are very different diseases, and they respond differently to fungicides. Early blight is caused by the fungus Alternaria solani. This fungus also causes early blight of tomato. Despite the name of the disease, early blight occurs later in the season, not early. To add to the confusion, late blight, caused by Phytophthora infestans usually occurs early in the season, although it can occur whenever environmental conditions allow. Late blight also occurs on tomato.

Management Of Early Blight Make sure plants have adequate nitrogen. Plants under nutrient or other stress will be more susceptible to early blight. When possible, rotate away from potato (and tomato), or grow on land that has not had potato for two years.

Early blight is favored by warm temperatures and long periods of high relative humidity. Research has shown that fungicide sprays applied early in the growing season, before the crop starts to flower, are of minimal control benefit. Later in the season, as the crop matures, the disease progresses more quickly and fungicides are important. The only fungicide organic growers have that is effective are the copper based fungicides.

One of the monst effective control for early blight for tomatoes is to use a mulch to keep soil from splashing up in rain onto the lower leaves.

Management Of Late Blight Late blight is one of the fastest moving and destructive diseases we have. It is similar in many respects to blue mold of tobacco, which is also very destructive.

Late Blight Forecasting Late blight is favored by frequent or long periods of leaf wetness from rain or dew, with temperatures in the range of 45 F to 80 F. The weather station measures rainfall, periods when humidity is over 90%, and the temperature during those periods. These conditions are converted in to a daily Severity Value. This indicates the likelihood of late blight developing. Late blight is predicted 7 to 14 days after 18 severity values have accumulated since crop emergence. In 1998, this threshold was reached on June 18, and the first reports of late blight outbreaks occurred in the last week of June.

Again, the only fungicide that works well for organic growers are the copper based products. I will have more on control of these diseases later.

TOMATO: CAUTION USING BOTANIGARD
BotaniGard has apparently caused injury on tomato transplants after being sprayed in the greenhouse. This is a bio-insecticide containing the fungus Beauvaria bassiania. A grower recently sprayed tomato plants with BotaniGard ES and obtained rather dramatic edema and yellowing along the veins of the leaflets and epinasty (downward curling) of the leaves. Daniel Gilrein, a researcher at Cornell's Horticultural Laboratory on Long Island has had reports of similar injury to tomatoes after application of BotaniGard. He sprayed some tomato plants with either the ES or WP formulation and similar injury developed several days after spraying. Injury was quite pronounced with the ES formulation and slight with the WP.

BotaniGard is an effective product, labeled for many crops, and is widely used in greenhouses. Our information about this problem in tomatoes is limited at this time, but we feel that caution is warranted.

John Howell and Rob Wick.

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.

Vegetable IPM Message
Ruth Hazzard, Editor. Charles Thayer, Assistant Editor.
The Vegetable IPM Message is published weekly from May to September and includes contributions from the UMass Extension Vegetable and Small Fruit Program faculty and staff, growers, and private IPM consultants.

Dave Handley edits the University of Maine Strawberry News letter.

I, (Eric Sideman) have adapted information from these sources and integrated it with reports I have received from MOFGA growers and modified it to be appropriate only for organic growers.

(About the author: Eric is MOFGA’s "extension agent" and can be reached at the MOFGA office to answer your questions about farming and gardening. Link to MOFGA Contact Page, or email Eric directly.)