Canadian Journal of Plant Pathology (2016) 38, 174-182

Alemu Mengistu, Xinhua Yin, Nacer Bellaloui, Angela M. McClure, Don D. Tyler and Krishna N. Reddy (2016)
Potassium and phosphorus have no effect on severity of charcoal rot of soybean
Canadian Journal of Plant Pathology 38 (2), 174-182
Abstract: Charcoal rot of soybean [Glycine max (L.) Merr.] caused by Macrophomina phaseolina is a disease of economic significance throughout the world. The effects of potassium (K) and phosphorus (P) fertilizer on disease development are unknown. Therefore, two separate trials were conducted in the field during 2008, 2009 and 2010 at Jackson and Milan, TN, USA to evaluate the effects of K and P on severity of charcoal rot. Rates of K (0, 45, 90, 134 and 179 kg K₂O ha^-1) and P (0, 22, 45, 67 and 90 kg P₂O₅ ha^-1) were used, with a sixth rate ranging from 0–22 for P and 0–37 for K equal to the recommended K or P fertilizer application based on annual soil testing. The colony forming units of M. phaseolina in soil indicated no significant response for any P treatments in five of six location-by-year and for K applications in all six location-by-year environments. Similarly, no significant response in tissue CFU for all P and K treatments in all six location-by-year environments was observed, indicating that the treatments had minor effects. The significant effects detected in the ANOVA were primarily due to major effects from year and location. The results showed that increasing the K and P application rates over both the recommended rate and control (0 kg ha^-1) did not affect severity of charcoal rot. The overall trends for many of the variables at both locations based on the slopes of the regression data were very weak, and the standard errors often were equal or larger than the observed slope and the R² values were very low. This study demonstrates that M. phaseolina populations were not significantly impacted by P and K applications in no-till soils and were not sensitive to routine P and K fertilizer application based on soil testing.
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Link to article at publishers website
Database assignments for author(s): Alemu Mengistu

Research topic(s) for pests/diseases/weeds:
environment - cropping system/rotation

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Macrophomina phaseolina