Effect of Previous Crop, Seedborne Inoculum, and Fungicides on Development of Stagonospora Blotch

Abstract

Stagonospora blotch of wheat has been difficult to control in the eastern United States. The objectives of this research were to evaluate the effects of field inoculum, seedborne inoculum, and seed treatment and foliar fungicides on Stagonospora blotch development and to develop more effective management strategies. In 1995 and 1996, similar experiments were established in “infested” and “clean” fields using two seed lots of Coker 9543 (“low” and “high” levels of seed infection) and six seed or foliar fungicide treatments. Planting in clean fields, planting seed with a low level of seedborne inoculum, treating seed with difenoconazole or triadimenol + thiram, and applying propiconazole or tebuconazole to the foliage all contributed toward reducing leaf infections by Stagonospora nodorum, severity of leaf and glume blotch, and incidence of S. nodorum in the harvested seed. Propiconazole alone was the least effective treatment. Planting in an infested field tended to negate the beneficial effects of low level of seed infection and fungicide seed treatments. Crop rotations and tillage that allow wheat debris to decompose before the next wheat crop along with difenoconazole or triadimenol seed treatment to reduce seedborne inoculum should be sufficient to avoid serious losses. In fields where wheat is grown every year, tillage and seed treatment would still be helpful, but a foliar fungicide at GS 8 may be necessary for adequate control. Applying an effective fungicide to seed appears to be a more efficient means of reducing seedborne inoculum than does producing seed with low levels of inoculum.

Quantifying the Effects of Fusarium Head Blight on Grain Yield and Test Weight in Soft Red Winter Wheat

“…The magnitude of the mean difference in test weight among SLB categories in this study was consistent across IND levels (nonsignificant SLB × IND interaction), suggesting that, although both FHB and SLB affect test weight (5,25,26,28), SLB did not affect the magnitude of the test weight reduction per unit increased in IND. This is probably due to the fact that the two diseases affect different plants parts (Stagonospora glume blotch levels were very low in all years of this study) and, as a result, likely impacted the size and weight of the wheat kernels, important components of test weight, at different times during the grain development process.…”

“…), are very common during the spring and early summer in wheat fields in Ohio, the Midwest, and other wheat-producing regions of the world (5,(12)(13)(14). F. graminearum and P. nodorum are both residue borne and both diseases are driven by rainfall and high relative humidity (18,28,42,45). In addition, they both have similar effects on grain yield and quality.…”

Fungal plant pathogens infecting barley and wheat seed from Alberta, 1995-1997

“…In Florida, Luke et al (1983) found decreased development of stagonospora (septoria) blotch, caused by S. nodorum, with either a 1-or 2-year rotation using uninfected seed, but not when S. nodorum infected seed was used. Similar results were also found by Milus and Chalkley (1997) in Arkansas where low (7%) and high (34-40%) levels of seed infection with S. nodorum led to significant leaf infection in an experiment planted in an area not cropped to wheat for at least the previous 4 years. They concluded that crop rotations should be combined with appropriate seed treatments to help prevent outbreaks of stagonospora (septoria) blotch.…”

A Multi-Aspect Comparative Investigation on the Use of Strobilurin and Triazole-based Fungicides for Winter Wheat Disease Control

“…Our results suggest that the weakest control of Septoria disease ant tan spot was in Tilt treatment. As was reported by Milus and Chalkley (1997) propiconazole was the least effective treatment against P. nodorum. In order of precedence between DMI fungicides in 1994 epoxyconazole showed the best efficacy against Septoria both M. graminicola and P. nodorum (Kendall & Hollomon, 1994).…”

“…As Arseniuk et al (1998) reported planting of highly infected seed resulted in more severe Stagonospora blotch than did the www.intechopen.com planting of healthy or only slightly infected seed; however, environmental conditions contributed considerably to disease severity. Planting in clean fields, using seeds with a low level of seed-borne inoculum in addition treated with fungicides and applying foliar fungicide application contributed toward reducing leaf infestation by P. nodorum, severity of leaf and glume blotch and incidence P. nodorum in the harvested seed (Milus & Chalkley, 1997 Table 3. The incidence and severity of Stagonospora blotch on winter wheat ears and grain infestation with P. nodorum in response to strobilurin-based and triazole fungicides During the last several years in Lithuania a clear predomination of M. graminicola over P. nodorum has been observed (unpublished data).…”