Integrated Pest & Crop Management Newsletter University of Missouri-Columbia Vol. 16, No. 12 June 30, 2006 Article 1 of 7 June 30, 2006 Soybean Diseases By Laura Sweets Soybean Seedling Blights and Root Rots This year many soybean plants seem to be off to a slow start. Dry soils, cold soils, sudden changes in weather conditions have slowed germination and emergence in some fields. When soybean germination and emergence is delayed soil pathogens such as Pythium, Rhizoctonia, Fusarium and/or Phytophthora have a greater opportunity to attack slowly growing plants. We are receiving questions related to poor emergence, uneven emergence, stunted plants and plants that are yellowing or even dying. On plants that are stunted, showing yellowing or scorching of lower leaflets and discoloration of root systems, Rhizoctonia and Fusarium appear to be the pathogens associated with these symptoms. See the May 27 issue of the Integrated Pest and Crop Management Newsletter for descriptions of the early season soybean diseases. Soybean Foliage Diseases So far, Septoria brown spot is the primary foliage disease showing up on soybean leaves. Symptoms seem to be most prevalent on the lowest leaves and spots may be very small. The typical Septoria brown spot lesions with fungal fruiting bodies evident in the center of the lesion aren’t showing up yet. Again with the current forecast of hot, dry weather for much of the state, Septoria shouldn’t be spreading very much. The disease is more likely to move under conditions of frequent rains, heavy dews and overcast days. We have not yet received any samples with bacterial blight or bacterial pustule. Although these diseases might show up after the heavy storms that moved through central Missouri the weekend of June 10-11. Laura Sweets 573-884-7307 ##################################################################### Article 2 of 7 June 30, 2006 CAFO Regulations Revisited by USEPA By John Lory, Commercial Agriculture Program and Plant Science Division The USEPA released for review proposed revisions to national regulations for concentrated animal feeding operations (CAFOs). This is the most recent step in a protracted effort to revise water quality rules that date back to the 1970s. The newest proposed revisions will fuel the continuing controversy on how to regulate animal feeding operations in the US. The USEPA approved revisions to the rule in 2003 but the changes were challenged in court by both agricultural and environmental organizations. Most of the 2003 revisions were upheld but the 2nd Circuit Court of Appeals ruled against USEPA on a number of key points. The recently released proposed changes are an attempt by USEPA to address the issues raised in the 2005 court decision. The most controversial element of the newest proposal is USEPA’s assertion that essentially all animal feeding operations must develop a phosphorus-based nutrient management plan. USEPA expands on its assertion that farmers only qualify for the agricultural runoff exemption if they have a nutrient management plan and can document through record keeping they are following the plan. Based on this assertion, USEPA expects all operations to implement plans that meet the regulatory standard, or potentially, the stricter Natural Resource Conservation Service (NRCS) comprehensive nutrient management plan (CNMP) standard. The assertion a farmer can invalidate the agricultural storm water exemption by over-applying fertilizer and/or failing to meet other "agricultural standards” on fields that receive manure could ultimately have implications for farmers that only use commercial fertilizer. This philosophy could be used to regulate fertilizer applications in future efforts to regulate agricultural water quality. THE PROPOSED REVISIONS ALSO ADDRESS TOPICS SUCH AS: * How to incorporate the nutrient management plan into a general permit. The rule establishes procedures for public comment on nutrient management plans under the general permit. * Design criteria for manure storages for new operations. It seeks to establish a "zero discharge" requirement for new swine, poultry and veal operations. This controversial proposal will reduce the regulatory viability of lagoons and other open storages. * Clarification of the standards for pathogen control. If adopted, the proposed rule changes will fundamentally change the national philosophy used to regulate most animal feeding operations. Once the national rule is adopted, Missouri will need to revisit its regulations and change them to meet requirements of the new national rules. Comments on the proposed changes will be accepted by USEPA for 45 days after the rule is officially posted in the Federal Register. The posting date will likely be July 3, 2006 which will allow comments through mid August. USEPA will have a public listening session on the proposed rule; the closest to Missouri will be in Ames IA on July 25, 2006. For more information on the proposed rules visit the USEPA Website http://cfpub.epa.gov/npdes/afo/aforule.cfm. These above observations are based on a preliminary reading of the proposed rule. Monitor publications and websites of commodity groups, Universities, agencies and other interested parties for more information on the proposed rules and their potential impact on your farm. John Lory Commercial Agriculture Program and Plant Science Division 573-884-7815 ##################################################################### Article 3 of 7 June 30, 2006 Corn Foliage Diseases By Laura Sweets After a slow start many corn fields have really "taken-off" and plants have increased substantially in size. Foliage diseases are showing up in scattered, isolated fields. So far anthracnose, Stewart’s bacterial wilt and common rust have been reported. The anthracnose has been on the very lowest leaves and doesn’t seem to be moving up in the canopy. The common rust has been on the very lowest leaves and slightly higher. In irrigated fields or if weather conditions change to a pattern of frequent rains, overcast days and heavy dews, fields should be scouted for rust. But with the current weather forecast of hot, dry weather for much of the state, the rust shouldn’t move much higher in the canopy. Generally speaking with the corn foliage diseases, the later in the season (especially the longer after pollination) that the foliage disease becomes established, the lower direct yield losses will be. Highest yield losses occur if diseases such as rust or gray leaf spot develop prior to pollination. Also, most of the corn foliage diseases are favored by extended periods of free moisture on the leaf surfaces. This moisture can be from rain, overhead irrigation or heavy dews that stay late in the day. Fields with poor air movement, river bottom fields or shaded portions of fields may also have higher levels of corn foliage diseases. Most of the control recommendations for minimizing losses due to corn foliage diseases are preventative measures such as planting resistant hybrids, rotating crops so the corn doesn’t follow corn in the same field or tillage to reduce the amount of infected residue left on the soil surface. Several fungicides are labeled for use on corn to control foliage diseases. These materials need to be applied at the first sign of disease and are primarily of economic benefit on seed corn rather than field corn. Fields with high levels of various foliage diseases may also show higher levels of stalk rot this fall. As harvest approaches, check fields which have had foliage disease problems for stalk rot and try to harvest problem fields promptly. Symptoms of Common Corn Foliage Diseases ANTHRACNOSE (COLLETOTRICHUM GRAMINICOLA) Infection is most common on lower leaves of young plants but may occur on upper leaves of maturing plants too. Anthracnose lesions tend to be brown, spindle-shaped lesions with yellow to reddish-brown borders. Concentric rings or zones are sometimes apparent within the diseased areas. Stalk symptoms appear as black linear streaks on the surface of lower internodes late in the season. HOLCUS LEAAF SPOT (BACTERIAL LEAF SPOT) Lesions usually are oval to rectangular in shape. Initially, they are dark-green and water soaked. Later they become dry and turn light brown with a reddish margin. The lesion resembles parchment paper. Holcus leaf spot may occur a few days after a rain storm but does not usually cause serious losses. COMMON RUST (PUCCINIA SORGHI) Circular to elongate, golden-brown to reddish-brown pustules develop on both upper and lower leaf surfaces. As plants mature, the pustules become brownish-black. The pustules rupture, revealing powdery brown spores. SOUTHERN RUST(PUCCINIA POLYSORA) Light, reddish-brown, circular to oval pustules develop primarily on the upper leaf surface. Eventually pustules rupture to reveal powdery spores. Later a brownish-black spore stage often forms in rings around the initial pustules. GRAY LEAF SPOT (CERCOSPORA ZEAE-MAYDIS) Lesions on maturing corn are pale brown to reddish-brown and blocky to rectangular in shape when compared to other corn leaf blights. The lesions typically are restricted by leaf veins giving the lesions parallel edges. Older lesions have a gray cast. Lesions may merge, resulting in large areas of dead leaf tissue. Lesions usually develop first on lower leaves but under favorable weather conditions, extensive leaf blighting over the entire plant may occur. NORTHERN CORN BLIGHT (EXSEROHILUM TURCICUM) Long, elliptical, grayish-green or tan lesions ranging from 1.0-6.0 inches in length develop on the lower leaves. As the season progresses, nearly all leaves of a susceptible plant may be covered with lesions, giving this plant the appearance of having been injured by frost. During damp weather, dark olive-green to black spores may be produced across surface of lesions. SOUTHERN BLIGHT (BIPOLARIS MAYDIS) Lesions are small, tan with buff to brown borders and somewhat elliptical in shape. Lesion appearance may vary greatly with genetic background of hybrids. Lesions may merge, blighting or killing large areas of leaf tissue. NORTHERN (BIPOLARIS ZEICOLA) Lesions are small, tan to reddish-brown and oval to circular in shape. Over time the lesions may become more tan to grayish-tan in color and be surrounded by a light to darkly pigmented border. EYESPOT (KABATIELLA ZEAE) Initial symptoms are small, translucent, circular to oval lesions with yellowish haloes. Later lesions develop tan to cream centers surrounded by a brown or purple ring with a narrow, yellow halo. Lesions may coalesce to from large areas of dead leaf tissue. Laura Sweets 573-884-7307 ##################################################################### Article 4 of 7 June 30, 2006 Potato Leafhopper in Alfalfa By Wayne Bailey Potato leafhopper (PLH) adult numbers continued to increase throughout the state during the past two weeks as recent storms transported additional PLH adults into the state from more southern locations. Alfalfa producers should scout fields at least twice per week to determine whether PLH numbers have reached the economic threshold level. If treatment is justified, producers should consider an insecticide application if the alfalfa is not ready for second harvest. From research conducted in Missouri, it was found that mechanical harvest of alfalfa (disc mower conditioner) substantially reduced numbers of PLH nymphs by greater than 90 percent. Adult numbers were reduced by about 60 percent because of their ability to fly out of the path of harvesting equipment. In situations where adult PLH return to feed on alfalfa following harvest, a stubble spray may be necessary to protect alfalfa regrowth. Fields most at risk from PLH damage are field seeded this spring and fields which have recently been harvested. Threshold levels for potato leafhopper in alfalfa vary with plant height and whether or not the alfalfa is a potato leafhopper resistant (PLH-resistant) variety. For traditional varieties (not PLH-resistant) the economic thresholds are as follows: ******************************************************* Average Alfalfa Height Number of PLH per Sweep (inches) (15-inch diameter net) ------------------------------------------------------- 0 to 3 0.2 (10 per 50 sweeps) 3 to 6 0.5 (25 per 50 sweeps) 6 to 12 1.0 (50 per 50 sweeps) 12 or taller 2.0 (100 per 50 sweeps) ******************************************************* The economic thresholds for PLH-resistant varieties are 3 times higher because PLH-resistant alfalfa varieties can withstand greater numbers of potato leafhoppers than not resistant varieties. This resistance is accomplished by the presence of small hairs on the leaflets and stems of resistant alfalfa plants. These hairs act a as physical barriers which holds the insect away from resistant plants and generally prevents the leafhoppers from probing and feeding on plant juices using their piercing-sucking mouthparts. Typically, migrating leafhoppers may land on resistant varieties at the same rate as traditional non-resistant alfalfa varieties, but most will leave the PLH-resistant varieties within 24 hours to find more suitable hosts. If a producer is growing a PLH-resistant variety, the following economic thresholds should be considered when assessing leafhopper numbers. ******************************************************* Average Alfalfa Height Number of PLH per Sweep (inches) (15-inch diameter net) ------------------------------------------------------- 0 to 3 0.6 (10 per 50 sweeps) 3 to 6 1.5 (25 per 50 sweeps) 6 to 12 3.0 (50 per 50 sweeps) 12 or taller 6.0 (100 per 50 sweeps) ******************************************************* *************************************************************************** PESTICIDES LABELED FOR USE ON POTATO LEAFHOPPER *************************************************************************** Chemical name Product Name Rates Preharvest Amount of product Interval (PHI) --------------------------------------------------------------------------- Cyfluthrin *Baythroid 2 0.8 to 1.6 7 days fl oz / acre Methyl Parathion *Chemnova Methyl 4EC see label rates 15 days Carbofuran *Furadan 4F 1 to 2 14 - 28 days pts / acre depending on rate Chlorpyrifos *Lorsban 4E 0.5 to 1 7 - 14 days pt / acre Chlorpyrifos *Nufos 4E 0.5 to 1 7 - 14 days pt / acre Chlorpyrifos *several formulations see specific see specific labels label Malathion Malathion 1.0 to 1.25 see specific lb a.i. / acre label for rates/PHI Zeta-cypermethrin *Mustang Max 2.24 to 4.0 3 days fl oz / acre Permethrin *Pounce 3.2EC 2 to 4 7 to 14 days, fl oz/acre depending on rate Gamma-cyhalothrin *Proaxis 1.92 to 3.2 1 day forage, fl oz / acre 7 day hay Lambda-cyhalothrin *Warrior 1.92 to 3.2 1 day forage, fl oz / acre 7 day hay Lambda-cyhalothrin *Silencer 1.92 to 3.2 1 day forage, fl oz / acre 7 day hay Lambda-cyhalothrin several formulations* see specific see specific lables labels --------------------------------------------------------------------------- *indicates Restricted Use. a.i. = active ingredient insecticide. *************************************************************************** By Wayne Bailey, Entomology 573-882-2838 office (573) 864-9905 cell ##################################################################### Article 5 of 7 June 30, 2006 Japanese Beetle in Corn By Wayne Bailey Economic Infestations of Japanese beetle are occurring in scattered locations throughout the state. This beetle was first found in the United States in 1916, following its accidental introduction from its native country of Japan. Japanese beetles are approximately 1/2-inch in length, metallic green in color with bronze or copper colored wing covers. They can be confused with the beetles of the green June beetle, but are smaller in size. Adult beetles emerge from the soil in May and June to feed for approximately 60 days. During this time the beetles mate and females deposit eggs in the soil. Each female may lay 40 to 60 eggs with larvae emerging in about 2 weeks. Larvae will feed on plant roots and decaying material before overwintering in the soil as 3rd instars. The following spring larvae quickly finish development, pupate, and emerge as adult beetles beginning in May. Japanese beetle adults often congregate in large numbers to feed on foliage and fruit of 300 to 400 different hosts, including ornamental, tree and small fruit, and corn and soybean plants. Typical feeding damage by the beetles is often seen as a lace-like pattern on host plant foliages as beetles avoid leaf veins when feeding. Beetles often begin feeding on the top of plants and move downward. Tassels and silks of corn can be severely damaged by adult feeding, whereas foliage feeding is common on soybean. Feeding on corn silks can disrupt pollination and result in substantial yield losses. Foliage feeding on soybean is less damaging, although small double-crop soybean may sustain economic damage. The grub stage of this pest will feed on plant roots of both corn and soybean with most feeding occurring in late June, July and August. Damage to plant root hairs may result in poor uptake of water and nutrients or be more severe and cause reduced stands through plant mortality. In field corn, an insecticidal treatment may be justified if during the silking period there are an average of 3 or more beetles present per ear, silks have been clipped to 1/2-inch or less in length, and pollination is less than 50 percent complete. The following insecticides are recommended for control of Japanese Beetle in field corn in Missouri. ******************************************************************* PESTICIDES LABELED FOR USE ON JAPANESE BEETLE ******************************************************************* Chemical name Product Name Rates: Amount of Product /acre (Unless otherwise noted) ------------------------------------------------------------------- cyfluthrin *Baythroid 2 1.6 to 2.8 fl oz bifenthrin *Capture 2EC 2.1 to 6.4 fl oz bifenthrin *Fanfare 2EC 2.1 to 6.4 fl oz zeta-cypermethrin *Mustang Max 2.72 to 4.0 fl oz methyl parathion *Penncap-M 2 to 4 pt permethrin *Pounce 3.2EC 4 to 8 fl oz gamma-cyhalothrin *Proaxis 2.56 to 3.84 fl oz carbaryl Sevin XLR Plus 2 to 4 pts lambda-cyhalothrin *Warrior 2.56 to 3.84 fl oz ------------------------------------------------------------------- * indicates Restricted Use ******************************************************************* Wayne Bailey 573-882-2838 office 573-864-9905 cell ##################################################################### Article 6 of 7 June 30, 2006 2006 Crop Injury Diagnostic Clinic July 25-26 & July 27-28 Bradford Research & Extension Center For registration information, contact Thresa Chism, 573-884-7945 or by e-mail at ChismT@missouri.edu For information on the content of the clinic sessions, contact Tim Reinbott, Superintendent of the Bradford Research & Extension Center, 573-884-7945 or by e-mail at ReinbottT@missouri.edu. ##################################################################### Article 7 of 7 June 30, 2006 Weather data for the Week Ending June 25, 2006 By Pat Guinan -------------------------------------------------------------------------------- | Monthly | Growing Weekly Temperature (deg. F) |Precip (in.)|Degree Days^ -----------------------------|------------|------------ Ext- Ext- Depart| Depart|Accum Depart Avg.Avg. reme reme from |Jun 1 from |since from Station County Max.Min. High Low Mean avg. |Jun 25 avg. |Apr 1 avg. ------------------------------------------------------|------------|------------ Corning Atchison 86 66 93 58 76 +2 | 2.38 -1.42 | 1410 +397 St. Joseph Buchanan 84 66 91 62 75 +1 | 2.81 -1.23 | 1345 +297 Brunswick Chariton 86 64 92 59 75 +1 | 2.26 -1.98 | 1371 +289 Albany Gentry 85 64 90 58 74 0 | 3.76 -0.09 | 1253 +218 Auxvasse Audrain 86 65 92 59 76 +1 | 5.65 +1.81 | 1342 +260 Columbia Boone 85 66 90 62 76 +1 | 4.01 +0.32 | 1367 +230 Sanborn Field Boone 87 67 92 64 77 +2 | 4.86 +1.14 | 1479 +313 Novelty Knox 85 65 91 60 74 0 | 3.39 +0.16 | 1212 +160 Linneus Linn 85 64 91 59 74 +1 | 3.70 -0.36 | 1244 +230 Monroe City Monroe 86 65 91 59 76 +2 | 3.93 +0.82 | 1267 +174 Versailles Morgon 89 65 92 60 77 +3 | 1.59 -1.94 | 1469 +287 Green Ridge Pettis 87 65 92 60 76 +2 | 1.42 -3.21 | 1417 +374 Lamar Barton 87 65 91 61 76 +1 | 4.44 -0.19 | 1510 +283 Cook Station Crawford 88 63 93 57 75 0 | 2.33 -1.18 | 1325 +109 Alley Spring Shannon 89 63 92 59 75 +2 | 2.16 -1.29 | 1320 +184 Round Spring Shannon 90 63 93 60 75 +2 | 0.91 -2.54 | 1334 +198 Delta Cape | | Girardeau 89 68 95 66 78 +1 | 2.35 -0.62 | 1489 +86 Cardwell Dunklin 89 72 93 70 80 +1 | 3.92 +1.27 | 1797 +236 Clarkton Dunklin 91 71 95 67 80 +1 | 1.96 -1.26 | 1698 +169 Glennonville Dunklin 90 71 93 67 79 +1 | 1.59 -1.32 | 1692 +168 Charleston Mississippi 89 70 93 66 79 +2 | 2.37 -1.14 | 1585 +217 Portageville- | | Delta Center Pemiscot 90 72 93 69 80 +1 | 2.03 -1.47 | 1768 +245 Portageville- | | Lee Farm Pemiscot 90 72 94 69 80 +2 | 1.92 -1.42 | 1772 +265 Steele Pemiscot 90 72 95 70 81 +3 | 2.14 -1.41 | 1858 +333 -------------------------------------------------------------------------------- ^Growing degree days are calculated by subtracting a 50 degree (Fahrenheit) base temperature from the average daily temperature. Thus, if the average temperature for the day is 75 degrees, then 25 growing degree days will have been accumulated. -------------------------------------------------------------------------------- Pat Guinan, Commercial Agriculture Program (573) 882-5908