This publication, formally known as the Plant Disease and Insect Advisory newsletter by the Oklahoma Cooperative Extension Service, underwent a title transition. It is now recognized by the title Pest e-Alerts.Entomology and Plant Patholog

Damicone, John

Hunger, Bob

Mulder, Phil

Royer, Tom A.

Royer, Tom

Walker, Nathan

SHAREOK repository

PLANT DISEASE AND INSECT ADVISCJRY Vol. 1, No. 18 ·· ·Department Entomology and Plant Pathology .· Oklahoma State University. 127 Noble Research Center Stillwater, OK 74078 Website: http://plants.okstate.edu/Pddl/advisory.htm KarnalBunt Update Bob Hunger, Extension Wheat Pathologist June 26, 2002 Recently I attended a meeting held in Texas on bunts and smuts. One of the highlights of the meeting was a field tour of the USDA-APHIS Kamal bunt (KB) testing facilities at Olney, TX. Below are listed several items I learned while on this field tour regarding KB from last year and this year. • According to APHIS, all of the grain from last year has been "handled." Grain from last year that tested positive for KB was steam flaked and used as feed. Grain that was co:. mingled (i.e., grain that tested negative for KB bunted kernels but came from the quarantined area or grain that was mixed with wheat from the quarantined area) was sold and exported to an overseas market. This was accomplished by moving the grain through a pathway normally used for sorghum. After the wheat was gone, the pathway returned to sorghum, which is a non-host of KB. • Over 100,000 cattle have moved through the quarantined area (the four counties just south of Oklahoma) during this past wheat season. This meant that cattle were removed from fields before the wheat reached the soft dough stage or the cattle were fed a KB-free food for a minimum of five days after removal from the field. • No KB has been found in the San Saba area in central Texas. • To date, only four wheat-grain samples (four fields) have tested positive for bunted kernels in the four quarantined counties near Olney. This is out of 708 samples processed as of June 18th. One KB bunted kernel was found in each four-pound sample from three of the fields, and three KB bunted kernels were found irt the four-pound sample from the fourth field. • Five of 116 wheat-seed samples have tested positive for spores. Remember, spore testing is conducted if wheat is to be used as seed. If wheat is to be used as grain, then the wheat is tested for the presence of bunted kernels. As of June 21st, no samples from Oklahoma have been processed. However, I received notice today that samples would begin to arrive from the Oklahoma Department of Agriculture early · next week. / Chinch Bugs Moving into Sorghum Tom Royer, Extension Entomologist Chinch bugs have been noted moving out of mature wheat fields in Kay County. Adult chinch bugs typically overwinter in bunch grasses and move into wheat in spring. They remain in the wheat until it matures, and then migrate to nearby corn or sorghum fields, usually as partially grown nymphs. Adult chinch bugs are black with a white "X" on their back, and measure 3/16 inches. Immature nymphs are smaller and range in color from red to brown, and have a white band across their back. They typically feed on the lower leaves of the plant, or below ground if there are cracks that provide access below the soil surface. They feed by sucking plant juices through their straw-like mouthparts and appear to inject a toxic substance with their saliva. Injmy symptoms on the feeding site may appear as reddish spots, and heavily infested plants appear to be wilting and drought stricken or injured by frost. Smaller plants are more vulnerable to injury, and sorghum seems to be more susceptible than com. As few as 2-3 chinch bugs can kill a seedling sorghum plant, but it will take 5-10 bugs per plant to kill larger plants. There are several options for control of chinch bugs. If a producer has had consistent infestations for several years, he/she should consider treating the sorghum seed with Gaucho® or Cruizer® insecticide to reduce the risk of economic injury. A seed treatment will not provide complete control of chinch bugs, but it will "slow them down" for about three weeks and give the sorghum a head start. For rescue management of chinch bugs, an insecticide can be applied as a border treatment or full field treatment. If the chinch bugs are moving in from a mature wheat field, consider a border treatment. The insecticide should be applied in a 30-60 foot strip along the boundary between the two crops. As the chinch bugs migrate, they will be controlled. One or possibly two applications may be needed. If the infestation occurs throughout the field, it should all be treated. With either method, ground applications using 20 to 30 gallons per acre and directed at the base of the plant provides vastly superior control compared to aerial applications. Consider banding the spray over the row. Several products are registered for control of chinch bug and are listed in the following table. Always r~member to read and follow all label restrictions. Control Suggestions for Chinch Bug in Sorghum Product Gaucho Cruizer Baythroid Karate Lorsban 4E Parathion (ethyl) SevinXLR Rate Product/A 8 fl oz product/ cwt seed 5.1 fl oz product/cwt seed 1.3-2.8 fl oz 3.84 fl oz 1-2 pt 0.75 pt 1-2 qt Pre-harvest Interval Conm1ercial seed treater only. 45 day waiting period for grazing. Commercial seed treater only. Do not feed treated seed. 14 days to grazing or harvest Do NOT graze or harvest for forage. 30 day waiting period for harvest 30 days if0.05 lb ai/A is applied; 60 days if over 0.5 lb ai/A is applied. 12 days for harvest or forage (aerial application only) 21 days for grain, 0 days for grazing Procure Fungicide Labeled for_ Pow(lery Mildew Control on Cucurbits John Damicone, Extension Plant Pathologist Procure (triflumizole) is a new triazole fungfoide marketed by Crompton/Uniroyal Chemical Co. that just-received registration for control of powdery mildew on cucurbits. Powdery mildew is a chronic problem on squash, pumpkin, and susceptible cantaloupevarieties; and is an increasing problem on watermelon. Triazoles are a systemic group of fungicides including Tilt, Nova, and Folicur which act similarly to inhibit strerolproduction in · fungi. Procure at 6 oz/ A has provided excellent disease control, similar to Flint and Nova, in field trials in Oklahoma and other states, The labeled rate is 4 to 8 oz/ A. Because powdery mildew can rapidly (in one season) develop fungicide resistance, rotating fungicide classes is recommended. Triazoles (Nova, Procure) and strobilurins (Quadris, Flint) should be alternated with each other or with - protectant fungicides (Bravo,sulfur) in spray programs for powdery mildew. On watermelon, it is important to know that triazoles do not control anthracnose or downy mildew. . . Because the manufacturer has not yet completed data requirements for Procure on cucurbits, plant-back restrictions are severe. Leafy and root vegetables may be planted 30 and 60 days, respectively, following application. All other crops, except those on which Procure is registered (tree fruits, strawberries, cucurbits) cannot be planted within one year. Vegetable Disease Update John Damicone, Extension Plant Pathologist The rains we have recently experienced have been favorable for disease development on vegetable crops. In my recent travels I have observed the widespread occurrence of bacterial spot and speck on tomato. These diseases are very similar and almost impossible to - distinguish. Symptoms appear as tiny, dark brown spots on lower leaves followed by leaf yellowing and eventually leaf drop. Bacterial spot and/or speck have been identified in commercial fields near OKC and in gardens and plots in central and eastern Oklahoma. Spray programs with copper products (Kocide, etc.), preferably in combination with maneb or mancozeb, should be maintained to minimize defoliation and fruit spotting. Watermelon anthracnose was observed in a large _watermelon field in southern Oklahoma. The grower had implemented a fungicide program soon after symptoms first appeared and the disease appeared to be localized. Anthracnose is a splash dispersed disease which can eventually cause spotting of fruit. Fungicide programs are critical in fields where anthracnose appears·or is a threat. Symptoms of mosaic virus were widespread in a watermelon field in southern Oklahoma. The virus was identified as papaya ringspot virus (PRSV), formerly known as watermelon_ mosaic virus 1. Symptoms were most severe along the edges of the field and included plant stunting, leaf stunting and narrowing, mild mosaic, and yellowing of plants. New growth on plants infected later was unusually upright, producing the so called "snake head" symptom. PRSV is one of three potyviruses that affect cucurbits. Potyviruses are spread by aphids that visit virus infected plants, acquire the virus on their mouthparts while probing, and transmit the virus to healthy plants within seconds while probing plants to find suitable hosts. Over 20 species of aphids are known to transmit PSRV, but the melon aphid is about the only species that colonizes cucurbits, Because the vectors are mostly transient, insecticide progratns have not been beneficial. for control of virus diseases. The only reported sources of PRSV are wild and cultivated cucurbits. Wild gourds were found along the borders of the field, but tested negative for the virus. Peanut Disease Update John Damicone, Extension Plant Pathologist Conditions have been favorable state-wide for the development of early leaf spot of peanut. Table 1 shows the cumulative infection hours from the MESONET early leaf spot advisory program (http://www.mesonet.ou.edu/premium/agmodels.html) for some of the peanut growing areas. It takes about 36 infection hours for infection. Symptoms then appear about 12-days later. The spray date indicates that spanish peanuts 30-days old or· rum1er varieties 45 days old on or before this date are candidates for a fungicide application. While it is early in the season for most growers to begin spray programs, growers with spanish varieties in fields previous cropped to peanuts may want to consider treatment. Expenses will end up being lower if the disease is controlled early in the season. A few symptomatic leaves may be evident at this time or appear sh01ily. These leaves probably will go unnoticed, but will serves as a source for rapid disease build-up should conditions again become favorable later in the season. Table 1. Cumulative infection hours for early leaf spot advisory program as of 20 June 2002 Location Infection hrs Sl!ray date Bumeyville 199.6 06/15 Hollis 117.4 06/06 Tipton 132.2 06/09 Altus 104.8 06/07 Mangum 119.8 06/07 Eric 142.6 06/08 Ft. Cobb 134.3 06/09 Hinton 218.2 06/13 Chickasha 205.2 06/14 Suggestions for Control of Grasshoppers in the Lawn and Garden Tom A. Royer, Extension Entomologist Grasshoppers are again a hot topic for Oklahoma ranchers and homeowners this year. It sometimes seems like these grasshopper nmnbers "exploded" overnight; however, such outbreaks actually have been "in the making" since 1997. Factors, such as rainfall, winter severity, presence of diseases and natural enemies and the number of eggs laid by the previous year's grasshopper population all interact to "create" this year's grasshopper outbreak. One question that I frequently get asked is, WHY NOW? My best conclusion is that we had a warm fall, which allowed grasshoppers to continue to lay eggs for a long time. Then, we had a very mild, dry winter that favored survival of the eggs. While we have had some heavy rains this spring, in general, the rains probably came too late to stimulate a disease outbreak. Finally there simply were not enough of the grasshopper's natural disease organisms around to create a disease outbreak. The. bottom line is that all of these factors add up to an explosion of very hungry grasshoppers! More than 80 species of grasshoppers occur in Oklahoma, but most never become pests. Homeowners usually battle four or five species in the home garden and landscape. They include the differential grasshopper, the red-legged grasshopper, the . migratory grasshopper, the two-striped grasshopper, and the Packard's grasshopper. The lifecycle of a grasshopper includes three stages; the egg, nymph, and adult. All but the migratory grasshopper produce one generation per year. The migratory grasshopper is unusual because it produces two generations each year, which makes it more likely to build up in numbers. Grasshopper eggs are deposited in the soil, often in clusters, during late summer and fall. The eggs begin development in the fall, then "go to sleep" during the cold part of the winter. They resume development as soil temperatures wann, and hatch from late April through July. Peak hatch usually occurs from late May to mid-June. Different species will hatch at different times during the spring and early summer. After hatch, a newborn grasshopper will have to shed its outer skin six times before reaching adulthood. This proc:ess is known as molting. Newly hatched grasshopper nymphs are very small, measuring less than¼ inches long, and may go unnoticed by the homeowner. They continue to eat, and grow as the spring and summer progress. The species of grasshoppers commonly encountered by homeowners typically feed on a variety of plants, but may favor some plants over others. According to Texas researchers, they tend to prefer the following plants: Butterfly bush, Holly, Russian olive, Liriope, Lavender, Hibiscus, Amarylis, Canna lily, Chrysanthemum, Daylily, Iris, Mahonia, Mondograss, Peach, Privet, Rose, Salvia, and Wisteria. Adult grasshoppers are very mobile, and will likely re-infest a yard several times if suitable food is present. When numbers are high, they may abandon any ''preference" and feed on nearly anything alive. As they get bigger and more mobile, they also become more difficult to kill with insecticides. This is when homeowners become frustrated, so it is crucial that control programs are initiated before they reach that stage. There are a number of products available for grasshopper control in the yard and garden. They include: Diazinon 25% EC, Orthene 9 .4% EC, and Sevin 50% WP The htbel MUST be followed becatjse some insecticide products can injure sensitive plants. There are products registered for perimeter treatments around household structures, such as Bayer Advanced Home® or Orthd Home Defense® that are effective as well. Another suggestion is to purchase floating pla~t covers made of Remay fabric. These can be used to cover your "prized" plants when grasshopp6r numbers are large. They are available at some nurseries or from mail-order garden suppliers. This infonnation was compiled from Grasshoppers in Gardens and Landscapes~Factsheet Ertt-'1038, written by Mike Merchant, Urban Entomologist with the Texas Agricultural Extension Service in Dallas, and from Grasshoppers in the Lawn and Garden-Entomology 487, written by Robert J. Bauemfiend, Extension Specialist with Kansas State University, Manhattan. ' Annual White Grub Control:· Options Tom A. Royer, ExtensionEntomologist Nathan Walker, Assistant Professor, Turf 1PM Southern masked chafers, (Cyclocep~ala lurida) the adult beetles that produce annual white grubs, are busy laying eggs in turf now. We have noticed increased egg-laying activity in Stillwaterthis past week, which 1nem;1s thatcontrol options need to be considered. There are a couple of options available for the' control of white grubs. The first option involves an early-season application of imidacloprid (Merit®) or. halofenozide (Mach 2®), which are registered for prevention of turf damage from grubs. Both insecticides take about 3 weeks to kill grubs but last for several months. They are most effective on small, newly hatched grubs. Both insecticides are also available to homeowners. In addition, imidacloprid is available as Bayer Advanced Lawn® Season Long Grub Control, as a ready-to-spread granual, or a ready-to-spray fonnulation. Halofenozide, available from The Scotts Company® and aclmowledged by the EPA to be a green chemistry or one which is environmentally friendly, is sold on a granual as Grub-ex or Grub-B-Gone. It is important that these two insecticides are watered in within one week of application with at least 1/4 inch of water, unless the turf received that much rainfall. Both insecticides are quite water-soluble, and dried residue readily washes ~ff the grass and into the root zone with rainfall. The masked chafer grubs will not hatc,h until early-mid July, so the insecticide must be in the soil at that time to provide maximum activity against them when they hatch. A delay of a week will allow sunlight to break down the product enough that it becomes less effective. Also, another group of grub beetles (Phylophaga spp.) have already been laying eggs for a month or more, so application of these two insecticide choices should not be postponed. If an early application of either of these two insecticides was not conducted, another option for control of grub beetles can be used later in the summer. The insecticides trichlorfon, sold as Dy lox®, or diazinon, formulated as a liquid or 5% granule, can be applied after the eggs. have hatched and when the small grubs are feeding near the soil surface. These two products don't persist for more than two weeks, so two applications spaced a month apart may be required to obtain satisfactory control. Diazinon can not be used on sod farms or golf courses, and all outdoor turf uses will be phased out after December 2003. Regardless of the insecticide choice, it is important to remember that grub injury can resemble other turf disorders, and grub presence should be confinned before initiating controls. To confirm the presence of grubs, peel back a strip of sod and examine the soil and thatch for their presence. Pay attention to bird activity in the spring; often crows or other birds will work grub-infested turf very actively in the spring. Oklahoma State University, in compliance with Title IV and VII of the Civil Rights Act of 1964, Executive Order of 11246 as amended, Title IX of the Education Amendments of 1972, Americans with Disabilities Act of 1990, and other federal laws and regulations, does not discriminate on the basis of race, color, national origin, sex, age, religion, disability, or status as a veteran in any of its policies, practices or procedures. This includes but is not limited to admissions, employment, financial aid, and educational servi~es. Issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Samuel E. Curl, Director of Cooperative Extension Service, Oklahoma State University, Stillwater, Oklahoma. This publication is printed and issued by Oklahoma State University as authorized by the Dean of Agricultural Sciences and Natural Resources. 

Plant disease and insect advisory, vol. 01, no. 18

Duthie, Jim

Shrefler, Jim

PLANT DISEASE AND INSECT ADVISORY Vol.1,No.21 Department Entomology and Plant Pathology Oklahoma State University 127 Noble Research Center Stillwater, OK 7 4078 Website: http://plants.okstate.edu/Pddl/advisory.htm Karnal Bunt (Kb) Update Bob Hunger, Extension Wheat Pathologist July 23, 2002 USDA-APHIS Report from Olney, Texas (dated 17 July, 2002): USDAcAPHIS has reported the following results from KB testing conducted in Olney, TX for the four county area (Archer, Baylor, Throckmorton, and Young): · • 125,027 head of cattle were tested and certified. • 798 wheat grain samples were collected and tested, with four samples testing positive (Baylor-2, Throckmorton-I, and Young-I). • 140 wheat seed samples were collected and tested, with six samples testing positive (Archer-2, Baylor-3, Throckmorton-I, and Young-0). The general tone of the update was that testing in the four county area was completed, and plans are being made for testing next year. I have heard of no update from the testing conducted in the San Saba area of TX. The last information I heard regarding that area (about 15 June) was that no KB had been found. Oklahoma KB testing update: • As of 19 July 2002, our lab has received 52 wheat grain samples as part of the national KB testing program. Oklahoma is projected to have a total of62 samples tested for 2002. Of the 52 samples received, 32 have been processed and all have been negative. Results from the first 20 samples tested have been reported to NAPIS. • I will be out of Stillwater from July 24 ~ July 31 st. If questions arise regarding Kamal bunt or the testing program, please contact Dr. Lany Singleton (405) 744-9956. Watermelon Anthracnose Outlook Jim Duthie, Extension Vegetable Plant Pathologist Jim Shrefler, Horticultural Extension Specialist Up to this point in 2002, gummy stem blight and anthracnose have been the most common foliar diseases in watermelon fields in Oklahoma. As usual, anthracnose appears to have been the most damaging. In some years in Oklahoma, downy mildew also causes extensive damage to watennelon crops but in those years, the disease typically does not appear before this part of the growing season. During the months of June and July, rain has been frequent and humidity has been high in many locations in the southeast district and around the state. As a result, watermelon foliage has often remained wet for unusually long peribds. Consequently, outbreaks of anthracnose have reached damaging levels in many crops. Crop$ that were planted in April and May and that have reached maturity or that will reach maturity before the end of this month have been particularly vulnerable. I Because of the persistent wet weaf1er during the past two months, the OSU watermelon anthracnose inodel ( http://agweatHer.mesonet.ou.edu/models/watermelon/default.html ) has recommended frequent application ofl fungicide for many locations in Oklahoma. The model is based on continuous assessment of both humidity and temperature in each county in the state. Fungicide application is the single mbst effective method of controlling foliar diseases such as anthracnose in an established watern:ielon crop. Except under wet conditions, fungicides will reduce the spread of anthracnose and ininimize effects on the quality and quantity of watermelon fruits. County extension educators cab recommend fungicides for the control of specific foliar diseases of watermelon and other cro~s. During the next month, many Oklah~ma watennelon growers may be able to reduce costs of fungicide application while minimizinig the risk of outbreaks of anthracnose. This can be done by carefully monitoring weather conditidns and by using the watermelon anthracnose model. Less I -frequent application is likely to be red:ommended by the model for many locations. Hot and dry conditions are likely to predominate! throughout the stat~ although localized showers remain possible. The National Weather Servi~e describes a familiar region of high pressure that has built up over the south-central plains. In mbst years, this high pressure region will persist for the next month or more; Moist air moving north from the Gulf of Mexico and from the southwest will be forced to flow to the east and west. i Outbreaks of foliar diseases of watermelon then will be unlikely except where localized thundershowers occur. Dig!er Wasps are Active Tom A. Joyer, Extension Entomologist I have received reports of legions of digger wasps "harassing" some people while they _are attempting to garden or mow their lawn. The call~rs' description of the wasp (about 1 ½ inches, black with yellow bands on the abdomen, brownish wings) sugg~sts that they are "Cicada Killers". These wasps ate solitary. The female wasp digs a ½ inch diametbr burrow in the ground, which she provisions with a I cicada or katydid I that she has stung and paralyzed, and; lays an egg on it. I She will then cover the burrow and start a new one. The eggs soon hatch, producing a legless larva that consumes the paralyzed, but living cicada that its mother so thoughtfully provided. Th~ grub overwinters inside a silken cocoon, then pupates in the spring and emerges as an adult wasp the following smmner. Female cicada killers rarely $ting, unless stepped on with bare feet or crushed. i The male wasp CANNOT STING, but is often the one that does all the "harassing." It establishes a territory that it defends from other male wasps, and waits for a female to fly by that it will attempt to mate.with.· When a person enters the wasp's territory, the male will fly back and forth, sort of "checking out" the new intruder. They usually leave once they determine that the person is neither a competing male nor a desirable female wasp. The problem is that as the as the person keeps moving, another male's territory is invaded, and the harassment starts all over again. These wasps prefer to lay eggs in bare, sandy soils. Mulching or planting of ground covers can reduce the problem. It is important to remember that the males cmmot sting, and the female wasps rarely sting. A homeowner may· be able to "live with them" if those facts are understood. As a last resort; the nest area can be treated with a labeled insecticide such as Sevin 50WP . or another labeled product such as Bayer Advanced Home™ or Ortho' s Home Defense. It is probably best to treat after sunset, when the wasps become less active. Usually, once the nests and females are killed, the males will leave the area. Oklahoma State University, in compliance with Title IV and VII of the Civil Rights Act of 1964, Executive Order of I 1246as amended, Title IX of the Education Amendments of 1972, Americans witl1 Disabilities Act of 1990,. and other federal laws and regulations, do.es not disctiminate on the basis of race, color, national origin, sex, age, religion, disability, or status as a veteran in any of its policies, practices or procedures. This includes but is not limited to admissions, employment, financial aid; and .educational setvices. Issued in furtherance of Cooperative Extension work, acts of May 8 and June 30, I 914, in cooperation with the U.S. Deprutment of Agriculture, Samuel E. Curl, Director of Cooperative Extension Service, Oklahoma State University, Stillwater, Oklahoma. This publication is printed and issued by Oklahoma State University as authorized by the Dean of Agricultural Sciences and Natural Resources. 

Plant disease and insect advisory, vol. 01, no. 21

PLANT DISEASE AND INSECT ADVISORY Vol. 1, No. 12 Department Entomology and Plant Pathology Oklahoma State University 127 Noble Research Center Stillwater, OK 74078 Website: http://plants.okstate.edu/Pddl/advisory.htm Wheat Disease Update Bob Hunger, Extension Wheat Pathologist May 14, 2002 On Tuesday, May Oi\ I traveled from Stillwater to the Burlington/Cherokee area and then south to Lahoma, Hennessey, Marshall, and back to Stillwater. On Friday, May 1ot11, I traveled south to the Tuttle-Chickasha-Apache area. I also rated breeder plots near Stillwater for reaction to leaf rust, and Brian Olson and I diagnosed numerous samples that were received in the Plant Disease & Insect Diagnostic Lab. Listed below are the highlights & observations from last week. Wheat streak mosaic virus (WSMV) definitely is more common this year in Oklahoma than it has been for quite some time, with samples received from Altus, Kingfisher, Lahoma, Hennessey, and Marshall all testing positive for the virus. Apparently the vector ofWSMV (the wheat curl mite) was more active over bigger parts of Oklahoma last fall than is usually the case. Although nothing can be done about these WSMV infections, remember for next fall that the two biggest contributors to WSMV are the occurrence of volunteer wheat in the late summer and fall, and early planting. Both of these contribute to a higher incidence of the mites, which in tum leads to more severe WSMV. Wheat leaf rust is at a high level around Stillwater ( on susceptible varieties, 6-8 on a scale of 1-9). In the field, I have seen levels on Jagger as high as 6 or 7 (approximately 65-80 MS/S), but it appears to me that for the most part, the crop should be sufficiently matme that losses · to leaf rust over most of Oklahoma will be minimal. The only place I saw a significant severity of wheat stripe rust is on some demo strips at the Lahoma Station. Everywhere else I've been I've either seen only very scattered stripe rust infections or none. Many samples and fields appear to have a combination of WSMV and root rots (mostly common, sharp eyespot, and Fusarimn root rots). Both of these (WSMV and root rots) would have been favored by early planting. In many of these fields, there also is a great deal of leaf ,spotting on leaves and stems. Isolations from these leaves and stems have revealed the pathogens associated with tan spot, septoria, and common root rot. I have seen some head trapping and leaf rolling consistent with Russian wheat aphid (RWA) here around Stillwater, but have not been able to actually find any R WA. Just as a point of interest, I also fom1d some fairly high levels of thrips infestations in rolled-up leaves, which according to the literature do not damage wheat. The best indication is to open the rolled-up leaves and look for scattered dark spots on the leaf surface, which is the frass ( excrement) of the thrips. Update on Ca!ncellation of Benlate Fungicide John Damicpne, Extension Plant Pathologist EPA approved the cancellation of ~enlate fungicide on Aug 8, 2000 when DuPont was not longer permitted to sell or distribute tµe product. The cancellation was voluntary and apparently the result of excessive lawsuits and resulting damages paid by DuPont over alleged crop injury caused by Benlate usage. EPA is pennitting continued sales of existing stocks already in the channels of trade until Dec 31, 2002l There is no end of use date for growers to use existing stocks. However, EPA has proposJd canceling tolerances (legal residues) on various crops between Jan 1, 2006 and Jan 1, 2009.1 These dates are based on the assumption that the last use by growers will be during the 2003 growing season. While it will not be illegal to use Benlate after 2003, benomyl residues on com1b.odities after the tolerance has been canceled will be illegal unless it can be demonstrated that it Jras applied before the end of 2003. The bottom line is that growers can purchase existing stocks lof Benlate through 2002 and use them through 2003. Any product not used by the end of the 20p3 growing season can be returned to DuPont for disposal, but the company will not reimburse the grower for the unused product and the grower must pay shipping costs. Waterme'lon Foliar Disease Control John Damichne, Extension Plant Pathologist I . . I Anthracnose and downy mildew have been the most important foliar diseases of wate4nelon in Oklahoma. However, powdery mildew is increasing in importance. Anthracnose has been a chronic probl~m in most areas of the state, although the disease has been virtually absent during the last three growing seasons. I fas able to produce a severe anthracnose epidemic in a fury.gicide trial at Perkins last year. Dowly mildew is a sporadic disease in Oklahoma. The fungus does :not survive in Oklahoma, but rather is wind-borne from soutliern production areas. Nonnally the disease does not appelr in Oklahoma until very late the growing season. How1ver, it has occurred as early as mid July. We will be keep~ng track of downy mildew outbreaks this season using the cucuJbit downy mildew forecast web page (http:l//www.ces.ncsu.edu/depts/pp/cucurbit) maintained by North Carolina State University. As of yet there are no reports of downy mildew outbreaks in Mexico or South Texas. However, idowny mildew has already been reported in Florida and South Carolina. / Powdery mildew has increased in ifnportance throughout watermelon producing areas in the southern United States. Typically, symptoms of powdery mildew on watermelon consist of a grayish-white, powdery growth covering the leaves. Affectcid leaves typically wither and die. However, symptoms may also consi~t of yellow blotches that became necrotic with sparse fungal developm~nt on the undersides of leaves. The i disease is difficult to identify in this form. Leaves within the lower canopy should be inspected for early disease detection. Usually a few whitish powdery colonies can be observed along with the yellow blotches. Control of foliar diseases on watennelon is becoming more complicated. We do know that a fungicide spray program is required to manage foliar diseases because adequate resistance is not available to any these diseases. Growers should consider making a preventive application of broad-spectrum fungicide with activity against all these diseases at flowering. Bravo or a tank mixture of thiophanate-methyl or benomyl and mancozeb would be good choices. Sprays with these fungicides can be continued on 14 day intervals or other fungicides with better activity toward a specific disease can be substituted as needed. Should rainy weather become problem or downy mildew become a threat, it may be necessary to shorten spray interval to seven days. Below is a table showing the relative effectiveness of fungicides against watennelon foliar diseases. Note that some of the product ratings changed from last year based on trial results from 2001. Brand Chemical Downy Powdery name name Anthracnose mildew mildew Aliette fosetyl-AL p G p Benlate benomyl G-E p F-G Bravo chlorothalonil G-E G F-G Dithane, Penncozeb mancozeb G-E G F Flint trifloxystrobin G F E Microthiol Special sulfur p p G-E Nova myclobutanil p p G-E Quadris azoxystrobin G F F-G Ridomil/Bravo mefanoxam+chlorothalonil G G F-G Topsin thiophanate-methyl G-E p P-F Benlate+ Di thane G-E G F-G Top sin+ Di thane G-E G F-G E=excellent, G=good, F=fair, P=poor (no control) Reducing the Costs of Disease Management Programs in Peanuts John Damicone, Extension Plant Pathologist Peanut growers will be under a new economic environment with the passage of the latest fann bill. While there is considerable uncertainty about program details and how to proceed, the biggest impact obviously will be reduced price for fanner stock peanuts. l have received several calls about how to reduce production costs. For disease management, my first answer is that there is ho single program or "package approach" that will work everywhere. Growers should evaluate fields on an individual basis to identify critical diseases that must be controlled in order to produce high yields. Disease management inputs should be applied against these diseases, ignoring other, secondary diseases that may not be causing real yield reductions. However, my feeling is that most growers have been doing this all along, particularly since 1996 when the first hit on farm price occurred. Meaningful reductions in disease control inputs will require a higher degree of management by growers. The following are suggested strategies, for diseases that growers in Oklahoma typically face. Seedling diseases - Seed treatment is 1sufficient to control seedling diseases. The addition of in-furrow application of fungicides has I not resulted in increased stand establishment or· yield in OSU trials, even in fields with a histo~-y of pod rot and or southern blight. Nematode diseases - Nematicide appl~cations for root-knot nematode should be based on soil test results. Ignore lesion and ring nematodes because treatments that provide a 11return on investment are not available. , I Foliar Diseases - Early leaf spot and web blotch are primary diseases that must me managed to produce high yields. The efficiency of spray programs for early leaf spot can be maximized using the early leaf spot advisory program (http://www.mesonet.ou.edu/premiurnY agmodels.htrnl). Contact your county Ag Educator for infonnation on how to use this weather-based program. The goal of a foliar disease program should be to control the disease durinig early and mid-season, and keep defoliation levels below I 50% by harvest. For runner varieties, it is highly unlikely that fields free of leaf spot on September 1st will benefit from late-s~ason sprays. Web blotch on Spanish varieties will require a regular fungicide program. . Peppdr spot should be ignored because yield losses from this , I disease have not occurred. ! i Southern blight - Where levels of th~s disease in excess of 5% (5 hits per 100 ft of row) are anticipated, a preventive fungicide program with Folicur, Moncut, or Abound should be initiated on or about August 1st . Most growets have already fine-tuned programs with these fungicides. An application of Omega to control $clerotinia blight will effectively substitute for a fungicide application to control southern blight. I Limb rot - This disease is a tough call. In most trials this disease has bee n of minor importance. Runner varieties in some high-yielding situations respo~d to fungicide programs (Abound, Folicur, Moncut). However, untreated plots in those trials have also produced good (two-t6n) yields. This disease is a good candidate for input reduction. I Sclerbtinia blight - Most growers realize that a resistant variety (Tarnlspan 90) or a moderately resistant variety (Tamrun 96) must I be planted in problem fields. Additionally, all varieties excel}t Tamspan 90 should receive a single application of Omega 4F at a minimum of 1 pt/ A as soon as the disease is first detec~ed. Tamspan 90 may also respond to Omega where vine growth is rank and the disease occurs early (July-August). Pod Rot - Resistant varieties such as 1f arnspan 90 and Tarnnm 96 should be planted in problem fields. Avoid problem varieties such !as Virginia types and AT-120. Fungicides targeted at pod rot have not provided economic returns. I I 2002 Grasshopper Hatch Uuderway Tom A. Royer, Extension Entomologist Clay Jones, Extension Educator in Bryan County is reporting the grasshopper hatch is underway, with nymphs about ¼ inch long. Over the last few years, Oklahoma ranchers have experienced economic numbers of grasshoppers in counties bordering the Red River. I expect that we will see larger numbers inwestem counties as well. Managing grasshoppers is tricky because it is difficult to accurately predict whether they will become enough of a problem to justify the expense of a spray application. Often, large numbers of nymphs will hatch, but as time, weather and natural enemies take their toll, they may not develop into a severe problem. Last year was a good example; grasshopper numbers were high in an insecticide demonstration plot in Jefferson County, but as the summer progressed, numbers declined to below economic numbers in both the treated and untreated check plots. The best time to control grasshoppers is now through about July 1, while they are immature. When they become full-grown mobile adults, they become nearly impossible to control. If the infestations are spotted early, an insecticide application in egg hatching areas may reduce numbers to the extent that few acres will require chemical treatment later on. Egg hatching areas include fencerows, grassy terraces and roadside ditches. It is difficult to judge whether control is economically justifiable. In rangeland, control is not justified unless numbers exceed 12-16 per square yard. There is a newly registered product, called Dimilin 2L, that can be used in rangeland to control grasshoppers. It can be applied as a Reduced Agent and Area Treatment (RAAT). This involves applying it as a strip spray, with coverage ranging from 50 to 90%. It works by interfering with the molting process of the immature grasshopper and must be ingested by the nymph to work. It will not work on adults. I must caution producers that Dimilin is not registered for use in improved pasture, and therefore is not legal to use. Even if it were legal to use, coverage would have to be at the 90% level because the forage grows rapidly enough to create a large amount of untreated foliage that would become available for consumption by the grasshoppers. Also, as hay is harvested, the product is removed with it. Other products that are registered for pasture should be used instead. They include Sevin XLR Plus or Malathion SE. For additional control rec01mnendations, consult the Extension Agents' Handbook of Insect, Plant Disease, and Weed Control, Publication E-832, pages 262-263. We have received a grant from the Animal Health and Plant Inspection Service to conduct 3 large-scale demonstrations for grasshopper control in rangeland. I will share the results of that work in a future Progress Report as the data becomes available. Grape ~erry Moth Model Results Phil MuTer - Extension Entomologist The table below represents model output for three monitoring sites fdr Grape Berry moth, respective degree-days for each, and larval ihfestations through May 13, 2002. LI . fcat10n ~t:r:Ir P rkins Degree-days 492.1 343.5 467.2 No. larvae per 100 clusters 0 0 0 Oklahoma State University, in compliance with Title IV nd VII of the Civil Rights Act of 1964, Executive Order of 11246 as amended, Title IX of the Education Amendments of 1972, Americans with IDisabilities Act of 1990, and other federal laws and regulations, does not discriminate on the basis of race, color, national origin, sex, age, religion,! disability, or status as a veteran in any of its policies, practices or procedures. This includes but is not limited to admissions, employment, fiqancial aid, and educational services. Issued in furtherance of Cooperative Extension work, act! of May 8 and June 30, 1914, in cooperation with the U.S. Department of Agriculture, Samuel E. Curl, Director of Cooperative Extension Scrvide, Oklahoma State University, Stillwater, Oklahoma. This publication is printed and i=ed by O~abom, S""' Uoi,=i<y ~ '"''"""' by ''1 DeM of Agrio,Jmral Sei~= m,d N•wral •-•es. 