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Volume 13-- 2001 Berry Notes is written by Sonia Schloemann except where other contributors are noted. Publication is funded in part by the UMass Extension Agroecology Program and grower subscriptions. A text version can be e-mailed to you if you contact Sonia Schloemann. Please cite this source if reprinting information. |
| Summer Edition 2001#2 Vol. 13, No. 7 May 24, 2001 Message from the EditorThe new UMass Extension Vegetable Team’s website is up and running. If you are a vegetable grower, you will want to check it out. It’s well organized, easy to navigate and contains excellent information. You’ll find it at http://www.umassvegetable.org/. Crop Conditions and Pest SummaryEnvironmental DataThe following growing degree day (GDD) and precipitation data was collected for the period, May 10 through May 16, 2001. Soil temperature and phenological indicators were observed on May 16, 2001. This information is intended to be used as a guide for monitoring the developmental stages and planning management strategies of pests in your location.
(Source: UMass Extension Landscape Message #11, May 18, 2001)
STATE WEATHER SUMMARY For the Week Ending Sunday, May 20, 2001Prepared by AWIS, Inc.
(Source: New England Ag. Statistics Service, New England Weekly Crop Weather Report, Volume 21, No. 3, May 21, 2001) Strawberries -- Sonia Schloemann, UMass Extension Fruit TeamGeneral: Scouting for two-spotted mite (TSSM), tarnished plant bug (TPB) are continuing. TPB nymphs are likely present, so be sure to check flower clusters by shaking them over a white surface. (More on this in last week’s Berry Notes.) TSSM thrive in dry, warm weather. Since temperatures have been generally low, mite populations have not increased dramatically, yet. This wet period will also slow them down. Once the rain stops, continue to check for TSSM infestations. Mite predators are an effective method for controlling TSSM in strawberries. However, if native predators are not resident in fields, TSSM can be controlled with the use of ultrafine 1% parafinic oils (e.g., Sunspray Ultrafine Oil or JMS Stylet oil). Remember, if you use one of these oil applications, DO NOT use in combination or in close proximity to the use of oil-incompatible pesticides such as captan; leaf damage or blossom/fruit injury will likely result. Primary Botrytis gray mold control is during bloom. Elevate® and Rovral® are very effective materials for the Botrytis fungus.
Eastern Flower Thrips are a relatively new pest on strawberries in the Northeast. Damage to strawberry fruit from this pest was rare until the mid- 90’s. Once identified, this pest has proved to be persistent and can cause high levels of damage in years when they are abundant. Damage from thrips infestation of fruit is most often seen as a dullness or bronzing of the fruit surface as a result of feeding. Light infestation can often go unnoticed. But, yield reduction of over 80% have been reported in the Midwest as the result of heavy thrips infestations. The Eastern Flower Thrips, is a tiny, slender, cigar-shaped insect. Nymphs and adults have the same general shape. Nymphs are wingless, whitish yellow when small, and yellow when fully grown. Adults are yellowish brown, 1/16 inch long, and have narrow wings that are fringed with hairs. While resting, the wings are folded lengthwise over the back. Eastern Flower Thrips do not overwinter in the Northeast. Similarly to Potato Leafhopper, Eastern Flower Thrips arrive each year as a result of long-distance migrations from southern states on weather fronts. Because of this migration factor, past infestation are not an indicator of future infestations. They are attracted to flowers of many different plants and on strawberry fruit, they feed on the tissue between seeds as the fruit expand. Thrips are often overlooked because they prefer to reside in protected sites, such as under the calyx. The life cycle can be completed in several weeks; there can be many generations per year. To determine if thrips control is needed, strawberry growers should sample for thrips at the same time as they sample for tarnished plant bug nymphs by examining flower clusters. Tap flowers onto a white or very dark plate or saucer, and look for the slender yellow thrips. Although the correlation between thrips counts and strawberry damage is not well understood, control is probably warranted only if populations exceed 10 thrips per blossom. Once berries are 1/4 inch in diameter, 50 randomly selected fruit should be picked and examined; control is suggested if an average of 0.5 or more thrips per fruit are detected. Insecticides used for controlling tarnished plant bug will likely also control thrips. Applications must be timed to avoid killing pollinators. Dacthal Available Again for Strawberries - Eric Hanson, Michigan State University Dacthal W-75 herbicide (DCPA) is again being manufactured and available for strawberries. This preemergent herbicide was used for many years by Michigan growers, but its manufacture ceased a few years ago. It is now being marketing by AMVAC out of Los Angeles. This is the same formulation and similar label instructions as the old label. Use rates are eight to twelve pounds. Dacthal provides good control of annual grasses and some broadleaf species on sandy soil, but control of most broadleafs, particularly on heavier soil, can be poor. The value of Dacthal is it can be applied to young plants with little danger of crop injury. (Source: Fruit Crop Advisory Team Alert, Vol. 16, No. 6, May 15, 2001) Brambles -- Sonia Schloemann, UMass Extension Fruit TeamAs mentioned in the beginning of this message, summer raspberries are at early pre-bloom, depending on variety and location. Growers should watch for evidence of leaf shredding on the newest leaves done by the adult form of the raspberry fruitworm. This small brown beetle later lays an egg which will hatch a small ‘worm’ that lives inside the raspberry fruit. Clean this insect up before bloom prevents the use of insecticides. Growers should also be scouting for cane borer adults by visually inspecting canes for live adults or puncture wounds, tarnished plant bug adults using visual inspections or white sticky traps, and two-spotted spider mites by looking at the under-side of the leaves in the lower 1/3 of the canes. See below for more information on cane borers. Cane Borers - two types of cane borers attack Raspberries. The raspberry cane borer is a 1/2" long, slender black beetle with an orange band just below the head and has long antennae. The female beetles girdle the tips of young raspberry canes by chewing two rings, about a half inch apart, around the stems about 3 to 6" below the top. An egg is inserted into the cane between the two girdled rings. When the larvae, or grubs, emerge, they feed inside the cane, tunneling downward, and eventually destroying the cane. Soon after the cane tips are girdled, they wilt, blacken, and may fall off. As soon as the wilted tips are noticed, they should be cut off, several inches below the lowest girdle mark. Remove the infested tips from the field and destroy them. Also eliminate any wild brambles near the field which may be harboring this pest. The red necked cane borer is 1/4" long, slender, and black with a "coppery" neck. Unlike the raspberry cane borer, it has short antennae. The red necked cane borer also causes a different sort of damage. The females insert an egg into young canes, usually within 10" of the base of the cane. They do not girdle the cane, but the presence of the egg, and later the grub, causes a swelling in the cane which can vary in length from 1/2" to nearly 3". These canes become weakened and may break off. Remove all canes which show the swelling and destroy them, and eliminate any wild brambles nearby which act as hosts for this pest. Insecticide sprays can be applied for adult cane borers just before bloom, but regular removal of the infected canes and elimination of wild brambles often provides adequate control. See pest management schedule for recommended materials and timing. Highbush Blueberries Post-pollination insecticide use options for New Jersey growers - Sridhar Polavarapu, Rutgers University A number of new insecticide options have recently become available for New Jersey blueberry growers. Growers need to pay close attention to their pest problems in order to choose appropriate and most effective insecticide option. This is especially important because many of the newer insecticides are very selective (not broad-spectrum), unlike the organophosphates and carbamates that we have been using so far in blueberries. For instance, Confirm 2F (tebufenozide) is effective only against caterpillars and has no effect on any other insects. Similarly, Provado 1.6F and Admire 2F (imidacloprid) is active against sucking insects such as aphids and some grub species. Here are a few guidelines you may consider for choosing appropriate insecticides during the post-bloom period: 1) If aphids are your primary concern, and you do not have a major caterpillar pressure or plum curculio at this time, then use Provado 1.6F in your first post-pollination applications during May until early June. If caterpillars and other pests are also a significant concern, you may have to use Diazinon, Guthion, or Lannate (see #3 below). 2) As you get closer to harvest, and if you want to stay on a calendar program for blueberry maggot management, your insecticide options are limited to Malathion, Imidan, or Lannate. Provado 1.6 has not been shown to be effective against blueberry maggot and is certainly not registered for this use. Lannate will provide effective control of blueberry aphids while Malathion has moderate activity. 3) If you want to use a broad-spectrum material in late May and early June (for caterpillars, aphids, leafhoppers, plum curculio etc.), you should choose one of Diazinon, Guthion, or Lannate. The pre-harvest interval (PHI) on Diazinon and Guthion (7 days) makes it difficult to use these products close to harvest. 4) Rotate insecticides as much as possible. This will minimize the risk of finding higher residue levels of any one product and reduce the chances of resistance development. Products such as Lannate and Provado are not registered in Canada; the tolerance levels for these compounds are therefore lower in Canada than in US. 5) Many of these new products have not been tested for compatibility or phytotoxicity on blueberries at this time. Therefore exercise caution in tank-mixing any of these products. A sensible approach would be to conduct a jar test for compatibility and evaluate on a few bushes for possible phytotoxic effects of potential tank mixtures before applying on large scale. In any case, pay close attention to all restrictions on the labels and follow the PHI as stated on the label to prevent illegal residues on the fruit at harvest. (Source: The Blueberry Bulletin, May 23, 2001 Vol. XVII, No. 6) Cranberry Fruitworm - Sridhar Polavarapu, Rutgers University Adults will continue to emerge over the next 4-5 weeks, and trap catches should peak by the end of May to early June. We are at the very beginning of the egg laying period. CBFW overwinters as a fully-grown larva about 3/8 inch long within a cocoon made of silk and soil particles. Pupation occurs during the early spring and moths begin to emerge during the second-third weeks of May. Male moths emerge 3-4 days earlier than female moths. Adults are brownish gray moths with a pair of white markings on each forewing. The eggs are pale-green, flat, and laid singly, most often along the inside rim of the calyx cup. Eggs hatch in 5-7 days and the newly emerged larva is pale yellowish-green. Upon hatching, larvae bore into fruit usually near the junction of stem and berry. The larva remains within the fruit until its contents are consumed whereupon it moves to enter another fruit. A single larva may feed on as many as five to eight berries before pupation. Infested berries are filled with larval excrement that can be seen near the entrance hole on the berry. CBFW infestations can be easily recognized by the presence of excrement filled webbings of infested and uninfested fruit. Infested fruit turn prematurely blue, shrivel, and often prematurely drop. Larvae drop to the ground under blueberry plants beginning the third week in June, and construct cocoons with silk and sand. There is only one generation each season. CBFW populations in both Atlantic and Burlington Counties have been spotty and at very low to moderate levels in most areas. Treatment is suggested only if significant populations exist, and should be applied approximately 4-6 days after the peak flight. These low population levels can be controlled with a single well timed application of insecticides such as Diazinon, Imidan, or Guthion. We are a few days away from the peak pheromone trap catches. Therefore, insecticide applications solely targeting CBFW are not necessary for at least another 5-10 days. (Source: The Blueberry Bulletin, May 23, 2001 Vol. XVII, No. 6 ) Lowbush Blueberries --Sonia Schloemann, UMass Extension Fruit Team As with highbush blueberries discussed above, growers should be setting traps for cranberry fruitworm. Our scouting program last season showed that this is a significant pest in our lowbush blueberry plantations. The procedure for timing sprays is the same as described in Highbush blueberries above. Other pests to watch out for this time of year include spanworm, and flea beetle larvae. Assess the severity of the problem using a sweep net. If spanworm catch is over 5 per 10 sweeps (on average) in bearing fields, or over 3 in non-bearing fields, consider a treatment with a B.t. formulation if only small larvae (instars) are found, or phosmet or methoxychlor for larger instars. The threshold for flea beetle larvae is higher, 30-50 per 10 sweeps. Phosmet and methoxychlor are also effective against fleabeetle larvae, but B.t. formulations are not. If Thrips damage was noted last year and the effected area staked prior to burning, an application of diazinon or malathion can be made when plant regrowth reaches 1/4 inch to 1/2 inch in height and repeated at 1/2 Inch to 1 inch in height. GrapesLong Island Update - Alice Wise, Cornell Cooperative Extension Week of May 14: Chardonnay ranged from 6-12". The dry weather has slowed shoot growth considerably. As a result, growers have been turning on the irrigation. Fungal disease pressure has been low to moderate. There have been very few reports of early season insect damage. Local AVA Approved: Congratulations to local wine industry members Richard Olsen-Harbich and Karen Meredith for spearheading the application for a Long Island AVA. It was very recently approved. This reflects and reinforces the commitment of local winegrowers to the production of quality wines. European Red Mite: We are approaching the period between 6" shoots and bloom where ERM becomes less of a concern. If shoots have passed the 6-8" mark unscathed, it usually becomes harder (though not impossible) to find significant mite populations. The rapid shoot growth of the prebloom period seems to dilute the population. As soon as shoot growth slows and the weather really warms up, populations begin to build again. Typically, early fruit set is when the first treatable populations seem to show up. Itís been said before - it is absolutely critical to scout your vineyards. Even if it is 15 minutes here, half an hour there, it is worthwhile. Stunted Shoots Part 2: In a previous newsletter, the causes of stunted shoots were reviewed. Culprits include Eutypa dieback, infestations of European red mite and thrips and virus infections. A fifth item can be added to the list ñ boron toxicity. While not common, boron toxicity has been seen from time to time in local vineyards. Boron is a micronutrient required in very small quantities. A rate of 1 lb./acre actual boron (soil applied) is not unusual in deficient situations. With a fertilizer like Solubor (20% boron), this would mean 5 lbs./acre of product. For 8x6 spacing, this works out to be only 2.5 grams per vine. Hand application is therefore risky for all but the bravest. Some growers get around the issue of uniform distribution and proper rate by either applying boron with the spring herbicide or blending it with other fertilizers. Foliar applied boron can cause toxicity symptoms as well if rates are too high and/or if the interval between two sprays is too short. Affected vines will be scattered throughout the block; in fact, one vine will display symptoms while its neighbor will not. This could be related to root architecture in that if roots are concentrated in an area with more boron fertilizer, uptake may be increased. Toxicity symptoms are distinct. Leaves become slightly puckered and rounded, losing the serration on the edges. Often necrotic flecks can be seen on leaves. Where injury is more pronounced, symptoms mimic Eutypa dieback. Shoots are spindly, leaves are tiny, chlorotic and cupped. Sometimes one side of a vine is more profoundly affected than the other. Where boron toxicity has been suspected, petiole and leaf analysis (results for each have been similar) has confirmed the diagnosis. Typically boron levels are 30 - 50 ppm with the lower end of that range more common on LI. Samples from damaged vines have been in the 60 - 65 ppm range. A little TLC should be used for damaged vines. Avoiding moisture stress will help. Most vines will outgrow the symptoms. Those vines with severe injury may well be compromised for more than one year. On affected vines, thinning or complete removal of crop is warranted. (Source: Long Island Fruit & Vegetable Update, May 18, No. 11) Disease Conditions and Considerations - Tony Wolf, Virginia Tech.Rain over the past weekend and yesterday has brought welcome relief to the dry weather that much of Virginia has experienced since early April. More than 2.5" of rain fell in parts of northern Virginia. The downside to the rain, especially the prolonged wetting (48 to 72 hours or more), is the very real threat of downy mildew and black rot infections. Coupled with the very susceptible stage of vine growth, and favorable temperatures, the disease pressure is SIGNIFICANT. It would be wise to review what fungicides were on your vines prior to recent rains, when the fungicides were applied, and what your current options should be. In our case, we went into the weekend rain with a prophylactic spray of mancozeb and Nova applied early the previous week. Because Nova is locally systemic, we were confident that it would be "rainfast" for continued black rot and powdery mildew protection through the rain; however, the Nova application would not protect newly emerging leaves. With over two inches of rain at our vineyard, we figure there's not much residual protection against downy from last week's mancozeb. Our strategy will be to get into the vineyard today or tomorrow and apply a combination of a fungicide for black rot and powdery mildew (probably a sterol inhibitor) and metalaxyl (one of the Ridomil formulations). Metalaxyl is only effective for downy mildew, but if you have concerns about downy, and we do, it's the Cadillac of materials. Mike Ellis, plant pathologist at Ohio State University, indicated that Ridomil can provide post-infection or curative activity if applied within 2 to 4 days of infection. Options for black rot and powdery mildew control are somewhat more varied and could include either locally systemic materials (such as the strobilurins or the sterol-inhibitors) or non-systemic protectants, such as mancozeb (black rot) or sulfur (powdery mildew). Northern Virginia is forecast to have a break in the rainy weather by Wednesday, but then a good chance of rain again on Thursday through Sunday. It makes sense to me to use a locally systemic fungicide during this rainy period to extend the period of effective protection. One might ask, "Why not use a strobilurin now, such as Abound, and get the protection against all three of our major disease threats?" The post-infection or eradicant quality of Abound appears to be inferior to that of metalaxyl. Thus, if in doubt about the level of protection that you had going into the rain, you might want to pay the money for the metalaxyl and sleep somewhat easier. I would encourage readers to review the comments of Wayne Wilcox that were presented in the last Viticulture Notes newsletter (http://www.ext.vt.edu/news/periodicals/viticulture/01marapr/01marapr.html) There is a wealth of tips and strategies outlined by Dr. Wilcox that can help you avoid diseases during this period. (Source: Virginia CooperativeExtension Grapenews, 22 May 2001) GeneralDry Soils and Weed Management - Rich Bonanno, UMass Extension Rainfall has been sparse and soils are quite dry. Herbicide performance under these conditions is often less than satisfactory. Following are some options for improving herbicide performance. If the herbicide you are using can be incorporated, this may be desirable. Incorporating a herbicide puts it in the zone where it is most effective and the need for rain or irrigation for activation is eliminated. For herbicides which cannot be incorporated, rainfall or irrigation is required within a few days to achieve activation. Be aware, that surface-applied herbicides will not work unless they are activated. If the soil is VERY dry, I suggest that the soil be irrigated prior to AND after the herbicide application. In other words, it helps if the soil is moist prior to herbicide application and activation. Lastly, sweet corn growers using atrazine plus Dual or atrazine plus Lasso can apply these herbicides at anytime from planting until the corn is 5" tall. If these herbicides are not incorporated and if irrigation is not available, it may be beneficial to wait until rainfall is anticipated before the application is made. Just be careful not to wait too long. Some emerged broadleaf weeds will be controlled but emerged grasses are difficult to control. Always check the herbicide label for advice on herbicide application and activation. (Source: UMass Extension Vegetable webpage; ‘Grower Alerts’.) Meetings Announcement: Major Community Supported Agriculture Conference Set for December. The third Northeast Community Supported Agriculture (CSA) Conference will be held December 7-9, 2001 at the Frost Valley Environmental Education Center in Claryville, New York. The conference will offer interactive workshops, expert trouble-shooting advice, intensive seminars and the opportunity to learn and share with nearly 400 other people interested in Community Supported Agriculture. Designed to help strengthen existing CSAs and help new ones get off to the right start, the program will provide a broad range of educational and networking opportunities for farmers, farm apprentices, CSA members, educators, and representatives of non-profit and government agencies. "I went to the last CSA conference with several members of my CSA core group, and we came back so excited and inspired that we made some really important improvements to our CSA," says Elizabeth Henderson, a CSA farmer from New York. New this year is a pre-conference, half-day "school" offering intensive, small-group sessions on CSA start-up, including technical assistance on legal, land-tenure and financial issues, and participatory working sessions to build a regional strategy for nurturing the CSA movement. The conference will also include trade show and display areas, youth programs, music, dancing, theater, and seasonal, regional food. Frost Valley, about 2.5 hours from the George Washington Bridge and two hours from Albany, offers a variety of accommodations, including economical bunk, family and inn-style lodging. CSA is a relationship of shared risk and decision-making between consumers and farmers. Consumers invest in a farm operation by paying in advance for a weekly share of the harvest. In return, they receive a steady supply of high-quality, nutritious food at an affordable price from someone they know. Farmers benefit from an assured market and infusion of cash at planting time, rather than at harvest. It is one of the most rapidly growing alternatives for small farmers, and an important tool for regenerating agriculture in the Northeast and elsewhere in the US. The conference is supported in part by a Northeast Sustainable Agriculture Research and Education (SARE) grant, and coordinated by the Northeast Sustainable Agriculture Working Group (NESAWG). Other project participants include the Robyn Van En Center at Wilson College, Just Food, Cornell University, and the University of Massachusetts Extension Agroecology Program. As additional information about the conference is available, it will be posted at the Robyn Van En Center website at www.csacenter.org To receive a registration packet (late summer) send an e-mail to bholtzma@together.net. Be sure to include your name and mailing address. |
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©Copyright 2001 University of Massachusetts Amherst, Massachusetts, 01003. (413) 545-0111. Produced and maintained by the UMass Fruit Team. This is an official page of the University of Massachusetts Amherst campus. |
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Eastern Flower Thrips
Sonia Schloemann, UMass Extension Fruit Team