Summer, 1990 (v2n4)
	Fertilizers and soil borne diseases. Huber, D.M. Soil Use and Management 6(4):168-173. 1990 This review paper summarizes the influence of crop nutrition and fertilizers on soil-borne diseases in annual cropping systems. Effects of nutrients have been confirmed by: 1) evidence of how different fertilizer practices affect disease severity; 2) comparisons of the mineral concentrations in resistant and susceptible cultivars; and 3) correlation of other practices (organic matter additions, crop rotations, etc...) and conditions that influence mineral availability with disease incidence or severity. The influence of fertilizers has been directly attributed to effects on survival and germination of the pathogen, and/or effects on its penetration and virulence. As plant nutrition is improved, other benefits accrue including: enhanced disease resistance, disease escape from rapid growth rates, and root exudates that support a beneficial soil microflora. Numerous examples are cited with references. Take-all of cereals (Gaeumannomyces graminis) has been extensively studied in this respect. A table of different soil conditions which increase or decrease this disease is provided. In general, take-all is more prevalent in alkaline, low-fertility soils and under conditions which increase nitrification such as nitrate application and liming. In contrast, eyespot (Pseudocercosporella herpotrichoides) and sharp eyespot (Rhizoctonia cerealis) are increased through top-dressing with ammonium. Adjustment of pH is another important means of preventing plant disease mainly through its effect on nutrient availability and uptake. Maintaining a high soil pH through liming (and in some cases through application of calcium and/or nitrate) is recommended for management of: club root of crucifers fusarium wilt diseases root and hypocotyl rots (F. solani, R. solani) rot and damping off caused by Pythium spp. Sclerotium rolfsii aflatoxin in peanuts soft rot of potatoes, carrot, bean (Erwinia spp.) Lowering soil pH through application of ammonium and manganese has been shown to decrease take-all of cereals, stalk rot of maize, common scab of potato, phymatotrichum root rot of cotton, verticillium wilt of various crops and various other diseases. Contributed by Dave Chaney [ Back | Search | Feedback ]