Legume ipmpipe Diagnostic Pocket Series Angular Leaf Spot Phaeoisariopsis griseola

Transcription

1 Angular Leaf Spot Phaeoisariopsis griseola Figure 1 Figure 2 Figure 3

2 Angular Leaf Spot Phaeoisariopsis griseola AUTHOR: H.F. Schwartz (Colorado State University) PHOTOGRAPHS: Courtesy of H.F. Schwartz & Bugwood.org [03/2011] COMMON HOSTS: Common Bean, Lima Bean, Tepary Bean, Scarlet Runner Bean, Cowpea, Soybean SYMPTOMS (ON COMMON BEAN): Figures 1 Angular leaf spot lesions are most characteristic on leaves, and appear as gray or brown irregular spots that may be bordered by a chlorotic halo. Lesions become necrotic and assume the angular shape characteristic of the disease. Black synnemata and conidia are produced in lesions on the lower surface of leaves (and other infected plant parts). Symptoms should not be confused with Nematode Angular Leaf Spot which does not produce any fungal structures in lesions. Figure 2 Dark brown elongate lesions may develop on petioles and stems of infected plants. Figures 3 Pod lesions are large, oval to circular, reddish brown spots, usually surrounded by a darkercolored border (Fig 3a); in contrast to other types of infection (e.g., common bacterial blight water-soaked lesions in Fig 3b). FACTORS FAVORING: Infected seed, infested debris and volunteers from previous seasons Rainstorms, high humidity and sprinkler irrigation Moderate temperatures with daily highs less than 28 o C [82 o F] ADDITIONAL DIAGNOSTICS AVAILABLE AT: Compendium of Bean Diseases, 2nd Ed.

3 Storm Damage Estimation Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

4 Storm Damage Estimation AUTHORS: H.F. Schwartz (Colorado State University), R.M. Harveson (University of Nebraska), and G.D. Franc (University of Wyoming) PHOTOGRAPHS: Courtesy of H.F. Schwartz [03/2011] Legume Type: Common Bean, Lima Bean, Tepary Bean, Scarlet Runner Bean, Cowpea, Soybean, Chickpea, Lentil. Protocols based on National Crop Insurance Standards; compare and document damaged and non-damaged portions of field or fields of the same variety, plant age Record variety, row width, emerged density in row Record stage of plant growth (VE to RH) Record dates of planting, storm event(s), evaluation Plant Stand (number/acre) Measure number of plants remaining (Fig. 1) in 1 bed by 20 ft = 1/1000 Acre at 5 representative sites in the affected area of the field; subtract number remaining from emerged plants to estimate % plant loss. Foliage, Stems & Branches (percent loss) Estimate percent of foliage (Fig. 2), stems and branches (Fig. 3) damaged (torn) or removed by the storm activity in 1 bed by 20 ft at 5 representative sites. Pods & Seeds (percent affected) Evaluate percent of pods for evidence of storm damage (as cuts, nicks, dents, bruises) on exposed outer pod walls (Fig. 4) and discolored or shriveled seeds on 10 to 25 plants at 5 representative sites (Fig. 5) ADDITIONAL DIAGNOSTICS AVAILABLE AT: Compendium of Bean Diseases, 2nd Ed.

5 Phytophthora & Pythium Phytophthora capsici & Pythium species Figure 1 Figure 2 Figure 3 Figure 4 Figure 5

6 Phytophthora & Pythium Phytophthora capsici & Pythium species AUTHORS: Julie R. Kikkert & Helene R. Dillard (Cornell University) and Steven L. Rideout (Virginia Tech) PHOTOGRAPHS: Courtesy of H.R. Dillard, S.L. Rideout and H.F. Schwartz (Colorado State University) [03/2011] COMMON HOSTS: Snap Bean, Lima Bean, as well as many cucurbit and solanaceous vegetables. SYMPTOMS (ON SNAP BEAN): Figure 1 Phytophthora blight symptoms first appear as large water-soaked lesions on the leaves. Leaves die and fall off the plant. Brown stem lesions and white powdery areas on stems are characteristic. Pods show white mycelial growth. Figure 2 Pods infected with P. capsici shrivel and become dry and leathery. Figure 3 Pythium species may infect planted seeds prior to germination, germinating seedlings, young plants, or older plants during flowering and pod stages. Symptoms appear as water-soaked areas on the hypocotyls and main root system which may extend above ground. Figure 4 The water soaked area eventually dries out, becomes somewhat sunken, tan to brown in color, and plants then wilt and die. Figure 5 Pods in contact with soil may become infected by Pythium, exhibiting water-soaking and fluffy white fungal growth (cottony leak). FACTORS FAVORING: Infested soil, equipment and irrigation water Wet, compacted soils Susceptible bean varieties Previous cropping history of squash, pumpkins, cucumbers, melons or peppers; disposal of culled cucurbits in a clean field Frequent high rainfall and warm temperatures greater than 25 o C (77 o F) favor postemergence as well as older plant wilts and pod rots; and Pythium damping off is generally favored by lower temperatures. ADDITIONAL DIAGNOSTICS AVAILABLE AT: Compendium of Bean Diseases, 2nd Ed.

7 Legume Insect Vectors of Viruses Figure 1 Figure 2 Figure 3 Figure 4

8 Legume Insect Vectors of Viruses AUTHOR: H.F. Schwartz (Colorado State University) and M.A.C. Langham (South Dakota State University) PHOTOGRAPHS: Courtesy of S. Bauer, J. Lawrence, A.C. Magyarosy, and F.B. Peairs Bugwood.org [03/2011] COMMON HOSTS: Common Bean, Lima Bean, Cowpea, Soybean, Pea, Lentil, and Chickpea are susceptible to one or more viruses transmitted by these types of insect vectors Vectors and Transmissible Legume Viruses: Figure 1 Various species of aphids (e.g., green peach aphid) can transmit viruses in the genera Alfamovirus, Carlavirus, Cucumovirus, Enamovirus, Luteovirus, Nanovirus, Potyvirus and Umbravirus such as: Alfalfa mosaic, Cowpea mild mottle, Bean common mosaic, Bean common mosaic necrosis, Bean leaf roll, Bean yellow mosaic, Beet western yellows, Clover yellow vein, Cucumber mosaic, Faba bean necrotic yellows, Pea enation, Pea seed-borne mosaic, Peanut mottle, Pea streak, Peanut stunt, Red clover vein mosaic, Soybean dwarf and Soybean mosaic viruses. Figure 2 Various species of leaf-feeding beetles (e.g., bean leaf beetle) can transmit viruses in the genera Bromovirus, Carmovirus, Comovirus and Sobemovirus such as: Bean mild mosaic, Southern bean mosaic, Bean pod mottle, Bean rugose mosaic, Cowpea chlorotic mottle, and Quail pea mosaic viruses; and Cowpea mild mottle virus, a possible Carlavirus. Figure 3 The whitefly (e.g., Bemisia tabaci) can transmit viruses in the genus Begomovirus such as: Bean calico mosaic, Bean dwarf mosaic, Bean golden mosaic, and Bean golden yellow mosaic viruses. Figure 4 Leafhoppers top (e.g., Neoalituris tenellus, Circulifer species) can transmit viruses in the genera Mastrevirus and Curtovirus such as: Bean yellow dwarf and Beet curly top; while various species of thrips bottom can transmit viruses in the genera Ilarvirus and Tospovirus associated with Red node and Bean necrosis mosaic viruses. FACTORS FAVORING: Planting adjacent to previous crops of legumes and other hosts of legume viruses such as alfalfa, clover, and vetch Planting legume seed carrying a seed transmitted virus (e.g., BCMV, PSbMV, SMV) Poor weed management in and around legume fields Temperatures with daily highs less than 32 o C [90 o F] Low to moderate moisture patterns that favor insect survival and movement ADDITIONAL DIAGNOSTICS AVAILABLE AT: Compendium of Bean Diseases, 2nd Ed.; Compendium of Chickpea and Lentil Diseases and Pests; Compendium of Pea Diseases and Pests, 2nd Ed.