No abstract

Several paper mills in Wisconsin have programs for spreading paper mill residuals (PMR) on land. A growing number of vegetable farmers recognize the agronomic benefits of PMR applications, but there have been no investigations on the use of PMR for control of vegetable crop diseases. Our objective was to determine the effect of PMR amendments on soilborne and foliar diseases of cucumber and snap bean grown on a sandy soil. Raw PMR, PMR composted without bulking agent (PMRC), or PMR composted with bark (PMRBC) were applied annually in a 3-year rotation of potato, snap bean, and pickling cucumber. Several naturally occurring diseases were evaluated in the field, along with in situ field bioassays. All amendments suppressed cucumber damping-off and Pythium blight and foliar brown spot of snap bean. Both composts reduced the incidence of angular leaf spot in cucumber. In a separate field experiment planted with snap bean for two consecutive years, all amendments reduced common root rot severity in the second year. In a greenhouse experiment, the high rate of PMRBC suppressed anthracnose of snap bean. These results suggest that the application of raw and composted PMR to sandy soils has the potential to control several soilborne and foliar diseases.

No abstract

Root rots of snap bean (Phaseolus vulgaris L.) and sweet corn (Zea mays L.) cause economic losses to farmers. This study was conducted to determine whether dairy manure amendments suppressed root diseases and to describe relationships between disease severity and soil characteristics. Field plots were amended with high or low rates of fresh or composted dairy manure solids in 2001 and 2002. Soils were collected at 2 and 12 mo after the first amendment and 2 and 6 mo after the second amendment. Greenhouse bioassays were conducted to assess severity of damping‐off (DO) of cucumber (Cucumis sativus L.) and root rots of bean and corn. Soils were analyzed for soil free (fPOM) and occluded (oPOM) particulate organic matter content, rate of hydrolysis of fluorescein diacetate (FDA), arylsulfatase activity, microbial biomass C, and water‐stable aggregation (WSA). Two months after amendment, all amendments (except the low rate of manure) reduced the severity of DO 30%, bean root rot 29%, and corn root rot 67%. Twelve months after amendment, amended soils were no longer suppressive. All amendments were suppressive after re‐amendment the following year and no longer suppressive 6 mo later. In Year 1, significant suppression was observed across all diseases when fPOM content was ≥12.1 g cm−3, FDA activity was ≥2.88 μg FDA min−1 g−1 dry wt, and microbial biomass was ≥91.6 μg C g−1 dry wt, and these levels were proposed as suppressive thresholds. Only the FDA threshold held up over all sampling times.

No abstract