Author: Darcy Telenko There are a number of fungal soybean diseases that can greatly impact seed quality. In Indiana, the most common are Phomopsis seed decay (Phomopsis spp.), Cercospora purple seed stain (Cercospora kikuchii); Frogeye leaf spot on seed (Cercospora sojina); Anthracnose (Colletotrichum spp.); Downy mildew (Pernospora manshurica); and various other secondary fungal invaders of injured pods including Alternaria, Fusarium, Cladosporium, and Penicillium. The tables below provides several descriptive characteristics to begin the diagnostic process and choose appropriate management recommendations. It is important to note, however, that although Purple Seed Stain is easily identified by the ‘signature’ purple symptom on the seed, accurate diagnosis of most of the fungal diseases on seed requires microscopic assistance offered by the Purdue Plant and Pest Diagnostic Laboratory (PPDL). The diversity of symptoms that can be observed on diseased soybean seed is shown in the example in Figure 1. In this image, all of[Read More…]
Author: Bob Nielsen Among the top 10 most discussed (and cussed) topics at the Chat ‘n Chew Cafe during corn harvest season is the grain test weight being reported from corn fields in the neighborhood. Test weight is measured in the U.S. in terms of pounds of grain per volumetric “Winchester” bushel. In practice, test weight measurements are based on the weight of grain that fills a quart container (37.24 qts to a bushel) that meets the specifications of the USDA-FGIS (GIPSA) for official inspection (Fig. 1). Certain electronic moisture meters, like the Dickey-John GAC, estimate test weight based on a smaller-volume cup. These test weight estimates are reasonably accurate but are not accepted for official grain trading purposes. The official minimum allowable test weight in the U.S. for No. 1 yellow corn is 56 lbs/bu and for No. 2 yellow corn is 54 lbs/bu (USDA-GIPSA, 1996).[Read More…]
Author: John Obermeyer Armyworm has been an occasional, yet unpleasant, surprise throughout this summer to those with grass crops, e.g, corn, orchardgrass, etc. One instance of late planted corn was documented in Pest&Crop 2018.17 (July 27). In previous late summers, we have received reports of established cover crops being denuded, in some cases from fall armyworm (different species than armyworm). Both species can consume large amounts of foliage as they “march” through a field. One major difference, armyworm feed only on grasses, while fall armyworm feeds on both grasses and broadleaves. Those with late season crops (ANYTHING GREEN) should be inspecting for feeding damage. This is very important for newly seeded forages and cover crops. Below is listing of high-risk situations until a killing freeze occurs: Newly seeded grasses of any kind, including but not limited to grass and mixed grass / alfalfa hay fields, and early planted small grains.[Read More…]
Authors: John Obermeyer and Christian Krupke Combines are rolling and wagons of grain are heading for dryers and storage. Already, questions have been received about soybean seed observed to be shrunken and/or discolored. Too, we typically get samples through the Purdue Plant and Pest Diagnostic Lab during harvest of seeds and asked to determine, which, if any, insect pest caused the damage. Bottom line…we need unharvested, damaged pods with the sample. For the last couple of years, there has been a noticeable population of green stink bug in some Indiana soybean fields. Both green stink bug adults and nymphs feed using their piercing-sucking mouthparts. They cause injury to soybean by puncturing pods and sucking fluid from the developing beans. This feeding also introduces bacteria, fungi and yeasts that may cause further damage. Seeds that do develop despite stink bug pod feeding may be smaller, shriveled, and/or discolored. This damage may[Read More…]
Author: Bob Nielsen Weather conditions strongly influence in-field grain drydown. Plant characteristics can also influence in-field grain drydown. Early grain maturation usually means faster in-field grain drydown. Later grain maturation usually means slower in-field grain drydown. elayed maturity of corn due to late planting or simply cool growing seasons often translates into delayed or slow drydown of mature corn grain prior to harvest and, consequently, higher than desired grain moisture contents at harvest. Wetter grain at harvest increases the need for artificially drying the grain after harvest which, in turn, increases the growers’ production costs and can delay the progress of harvest itself. Conversely, an early or rapid drydown of the crop decreases growers’ costs and facilitates early or at least timely harvest of the crop prior to the colder and, often, wetter conditions of late fall. At the moment, the 2018 end of season is shaping up to look[Read More…]
AUTHORS: Jim Camberato, Shaun Casteel, Gail Ruhl, and Darcy Telenko Soybeans in Indiana often show potassium (K) deficiency symptoms during seed fill – leaf margin chlorosis to necrosis. Although the symptoms are classic in many respects, one aspect of their occurrence differs from the norm — the symptoms are occurring on the youngest uppermost leaves, oddly enough, rather than on the older lower leaves (Figure 1). As the deficiency continues and the severity increases, the necrotic leaf margins can simply drop off the plant resulting in a ragged or tattered appearance (Figure 2). Iowa State Extension specialists described this condition in Iowa several years ago, referring to it as ‘Soybean Top Dieback’. X.B. Yang and John Sawyer describe the condition in the newsletter article Soybean Top Dieback Shows up in Iowa Again. Low soil test K has been found in association with Soybean Top Dieback. Samples from Indiana fields exhibiting K[Read More…]
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