Eric Sideman's Pest Report
June 7, 2003

(View List Of All 2003 Pest Reports)

Introduction

--Eric Sideman

COLORADO POTATO BEETLE

In the mean time I think some growers will have a hard time. But, most will be able to control the CPB with other practices and materials. Remember the life history when choosing your approach. The beetle overwinters as an adult hibernating a few inches deep in the soil. In the spring the adults become active about the same time that potatoes start sprouting (now). At that time they cannot fly and so they crawl around looking for potatoes, or eggplants which they really like. A few weeks later they lay small masses of orange eggs on the underside of the leaves. The eggs hatch into larvae which do most of the damage.

The very small scale grower is still best served by hand picking the adults early in the spring and squashing the egg masses. Larger scale growers should rotate crops, and if new isolated fields can be used that are more than a half mile from where potatoes where the previous years that should offer some pretty effective control. Also, since the beetles crawl out of hibernation, a ditch lined with plastic can serve as a barrier between the new field and the old one as the beetles fall in and cannot crawl on the slippery plastic. Thick organic mulch also serves to reduce populations as the adults have trouble crawling out of hibernation.

A new product is on the market fill the gap left by the lost Bt. It is a new formulation of Spinosad called Entrust. (See the Pest Report from last week for a discussion of Entrust). The old formulation has had good reports but was unavailable to organic growers because of prohibited inert ingredients. Spinosad is a product that is a product of fermentation of a naturally occurring soil microbe. The material works by activating nicotinic acetylcholine receptors leading to neuromuscular fatigue and paralysis of the insects. It has low human toxicity and low environmental impact because it degrades relatively quickly in the soil. It is active against caterpillars, some beetle and fly larvae, and even leaf miners because it is absorbed into the plant leaves. Even when Novador comes back I think Entrust will serve well in rotation with Novador in order to avoid build up of insect resistance.

When you see the first egg masses flag them and watch their development. When the majority of them hatch, spray Entrust. Then spray again when the last of them hatch. If you are isolated and no adults fly in from other fields that may be all the spraying you need for the season. The good news with Entrust is that the timing is not as crucial as it is with Bt. If you miss these early egg hatches you are not up the creek. Entrust will work on adults and large larvae, unlike the Bt.

FLEA BEETLE UPDATE

Weekly dissections of field-collected beetles indicated that females began producing eggs around the first week in May. The female beetles lay their eggs at the base of the stem of brassicas, and the larva develop in the soil, feeding on root hairs and roots of brassicas. It is possible that the feeding by larvae impacts overall growth and yield of the plants, especially for crops that are in the field for longer periods of time. In our research this summer, we plan to evaluate the impact of larval feeding on the crop, as this has not been well documented. Currently, no management options exist to control immature stages of the flea beetle. We will be evaluating several insecticides that target the adults, larvae, or both stages.

Waxy cole crops such as cabbage and broccoli are more susceptible to flea beetles in the early stages, but tend to be less heavily fed upon as they grow. In other words, damage is most severe to seedlings and often plants can out grow the damage, but with salad greens any damage lessens marketability. And, these non-waxy brassicas such as Asian leafy greens continue to be attractive and very susceptible throughout their growth. The most effective control of flea beetles is using spunbonded row covers to exclude the beetles. Place the row covers on at the time of transplanting or seeding and seal the edges with soil. For the most part flea beetles do not overwinter in cultivated fields. They spend the winter as torpid adults in leaf litter in windrows, headlands, treelines, fencerows, etc. Adults emerge from overwintering sites in early spring and begin feeding on the first cruciferous weeds. Reducing leaf litter and controlling weeds can reduce populations. Perimeter trap cropping can work with flea beetles because they move into the field from the edges. Completely encircle the field with Chinese giant mustard 1 to 2 weeks before establishing the main crop to allow the trap crop to reach an adequate size before the crop does.

For foliar sprays, one beetle per plants is a conservative threshold; five beetles per plant has been shown to reduce head size and yield in broccoli. Organic options include pyrethrin (e.g. Pyganic Crop Protectant), neem (e.g. AZA-Direct, Neemix, etc.), and also Surround has shown some supprssion. Trials conducted at the CT Agricultural Experiment Station showed that high rates of Pyganic suppressed moderate levels of flea beetles, although they did not find this effective in experiments at UMass. They have received grower reports of successful suppression at 40 oz/acre with a spreader sticker.

-- Modified from a report by Caryn Andersen and R Hazzard, Dept of Entomology, University of Massachusetts

APHIDS : BUG VS. BUG, BIOLOGICAL CONTROL AND IDENTIFICATION

In crop situations where a broad spectrum insecticide is not being used, aphids can be controlled by naturally occurring predators such as lacewings, ladybeetles, hover flies, and tiny parasitoids. Several biocontrols of aphids are sold commercially and can be used to augment a system of natural control.

Damage: Aphids will feed on foliage and stems of plants. Plant damage can appear as curling and stunting of leaves. In addition to the ability to transmit viruses, aphids cause direct damage by feeding on plant sap to acquire the proteins and sugars needed for their reproduction. Aphids secrete excess sugars in the form of sticky 'honeydew'. Honeydew supports the growth of black sooty mold that affects plant photosynthesis, possibly reducing plant yields. Removing sooty mold from fruit increases handling time and can possibly render fruit unmarketable.

Life cycle: In greenhouse production, aphids are very prolific. Instead of reproducing by eggs, female aphids (stem mother) give birth to live nymphs (3-10/day) that start to feed immediately. Within a week, this offspring will be ready to reproduce. Aphids can have two forms: winged or wingless. As colonies enlarge, aphids develop wings to migrate to less populated areas in the crop.

The most outstanding characteristic for identifying aphids is by the two cornicles ("tail pipes") on the rear of their abdomen. Color is variable among species and is not accurate for identification. As aphids increase in size, they shed their exoskeletons (cast skins). These white cast skins, often mistaken for adult whiteflies, can be found on leaves or stuck in honeydew excretions.

Description of Aphids: A hand lens (at least 16x ) is needed to identify these characters.

Potato aphid (Macrosiphum euphorbia) - Large aphid, adults are 2.5 to 3.5 mm long. The antennae are longer than the body and the cornicles are very long and cylindrical. Aphid color varies from green to pink forms.

Green peach aphid (Myzus persicae) - To differentiate from other species, look for a rectangular indentation on the head between the antennae. The adult aphid is light to dark green and cornicles are slightly darker than the rest of the body. Aphids may also appear pink or orange depending on the host.

Melon aphid (Aphis gossypii) - Antennae are shorter than the length of the body. Color can vary from green, blue-green to gray green. The cornicles are of adult aphids are short and entirely black.

Monitoring: Plant monitoring should begin at the seedling stage and continue through the duration of the crop cycle. Start plant inspection on lower leaves and continue up the plant to the growing tips. As aphids feed on growing tips, the leaves curl, sometimes looking like virus symptoms.

Yellow sticky cards are useful in detecting winged aphids. Hang sticky cards 4 - 6 inches from growing tips. IPM Labs (www.ipmlabs.com) sells a chart with drawings of important insects found on sticky cards. Unfortunately, winged adults on sticky cards may indicate that there are crowded populations already established in the crop and they are migrating to less populated areas. The presence of ants in the greenhouse may indicate aphid development, since the ants feed on the excreted honeydew and thus protect the aphids. When introducing biological controls, place them in an area protected from ants and control ants with baits or traps.

Biological Control: Several long-lasting and effective biological controls are commercially available for aphid control.

Parasitoids for Aphid Control: Caution: Parasitoids for aphid control are very species specific. Identify the aphid species infesting your crop before ordering from your supplier.

Aphidius colemani - Used to control green peach aphid and melon aphids. This tiny wasp lays an egg in the aphid. The egg hatches into a larva that spins a cocoon, producing a new wasp. The wasp exits the aphid body, leaving behind a brown shell called an aphid mummy.

Aphidius ervi - Used to control potato aphids. This parasitoid has a similar appearance and life cycle as Aphidius colemani. This parasitic wasp is about twice the size of A. colemani.

Aphelinus abdominalis - Used to control larger aphid species such as potato aphid and glasshouse potato aphid. This wasp is about 3 mm long. The main advantage to using this parasitoid is that the female adult will parasitize for several weeks and it will also feed on the aphids.

Predators for aphid control:

Ladybeetles (Hippodamia convergens): - Ladybeetles are sold as adults in pints, quarts and gallons. A general predator, ladybeetles are effective for cleaning up hot spots. They also feed on scales, thrips, and other soft - bodied insects.

Lacewings (Chrysoperla rufilabris) - Lacewings are sold as eggs, larvae. The larvae are voracious predators known as "aphid lions". They will also feed on mealybugs, scales, spider mites and thrips.

Predatory Midge (Aphidoletes aphidimyza)- This midge is sold as the adult to be released in greenhouse. The adult midge lays eggs near aphid colonies and the orange larvae feeds on aphids.

A partial list of biocontrol suppliers Crop King,, http://www.cropking.com (330) 769-2002 fax: (330) 769-2616

Green Spot, http://www.greenmethods.com (603) 942-8925, FAX (603) 942-8932

Hydrogardens. http://www.hydro-gardens.com (888) 693-0578, FAX (800) 694-6362

International Technology Services, http://www.bugsandbees.com Ph. (800) 375-1684, FAX (303) 661-9543

IPM Laboratories, Inc. http://www.ipmlabs.com Ph. (315) 497-2063, FAX (315) 497-3129

Koppert Biological Systems, http://www.koppert.nl (800) 928-8827

For a comprehensive listing of biocontrol suppliers and information visit this website: http://www.anbp.org. This is the site of the The Association of Natural Biocontrol Producers (ANBP), a professional association representing the biological pest management industry. ANBP membership includes producers, distributors, and in addition, users of natural enemies and researchers.

Tips for using biocontrols effectively:

• Discontinue the use of residual pesticides, 4 - 6 weeks prior to introducing biocontrols - check residues with suppliers
• Identify the aphid attacking the crop
• Start introducing biocontrols when pest populations are low
• Follow supplier recommendations for release rates
• Disperse biocontrols on the day of receipt

--Cathy Thomas, Integrated Pest Management Program Bureau of Plant Industry, PA, published in Vegetable and Small Fruit Gazette June 2003 Vol. 7 #6

INSECT CONTROL FOR EARLY SEASON ROW COVER SWEET CORN

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.

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. We will have more information on scouting techniques and corn pest control in future Pest Reports.

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.

--Modified from a piece by John Mishanec, Area Vegetable IPM Educator, Cornell Cooperative Extension, Capital Vegetable News, Vol. 5:1-- Spring 2003.

STRIPED CUCUMBER BEETLE COMING SOON

Early season infection. Pumpkin plants at the cotyledon and first 1-2 leaf stage are more susceptible to infection with bacterial wilt than older plants, and disease transmission is low after about the 4-leaf stage. Wilt development is strongly influenced by the dose of the pathogen that the plants receive. Typically, only a relatively small proportion (1-10%) of overwintering beetles carry the Erwinia pathogen and are able to infect plants. The higher beetle density during early plant growth, the more severe the incidence of wilt. Beetles that discover a host plant will release an aggregation pheromone that calls others to their spot. Groups of beetles feeding, wounding and defecating on a single plant are more likely to transmit disease, acquire the pathogen, and transmit it to other plants.

Thresholds and foliar controls. Beetle numbers should be kept low, especially before the 5-leaf stage. Crop rotation to a field at a distance from last year's cucurbits reduces beetle numbers significantly and may eliminate the need for controls. Beetle numbers tend to build up when vine crops are planted in the same or nearby fields year after year. Conventional IPM systems have relied on scouting frequently (at least twice per week) and treating after beetles colonize the field. To prevent bacterial wilt, we recommend that beetles should not be allowed to exceed one beetle for every 2 plants in susceptible crops. This is a lower threshold than is needed to prevent significant foliar damage. Less wilt-susceptible crops will tolerate 1 or two beetles per plant without yield losses. Proper timing can be difficult: growers have to be ready to respond quickly in a very busy time of the season, and weather or field conditions can delay sprays. However, foliar sprays remain a viable option (see below).

Row covers are being used by many growers of curcubits to prevent early season attack by the cucumber beetle. Remember, the row covers need to be removed to weed periodically, and removed for the season when flowers appear to allow pollination.

Scouting and using foliar sprays: 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 your local Extension office 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.

Controls: For organic growers, kaolin (Surround WP) provides a new option. Pyrethrin (Pyganic Crop Spray 5.0 EC) is another option but to me since it is a broad spectrum pesticide is mubh less attractive. Perimeter trap crops (see below) are another option. NOTE: available Rotenone products do not meet inert ingredient guidelines 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.

--Modified from a report by Ruth Hazzard

PERIMETER TRAP CROPPING FOR CUCUMBER BEETLE MANAGEMENT

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 (Pyganic) 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.
• 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.

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.

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