Diseases of farm crops

Key words diseases of crop plants, disease symptoms, disease cycles, disease control, fungicide resistance. 

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Table 6.2 outlines some of the main diseases affecting farm crops and both chemical and non-chemical methods of control. 

Perennial farming systems with tree, bush or vine crops also provide niches for short and longer term intercropping. In addition to the use of cover crops on the orchard floor of many crops including apples (Hartley ef al. 2000) and wine grapes (Bugg ef al. 1996), plantings of commercially and environmentally valuable species within or around the orchard have also been used for pollination, disease and pest control (Finckh and Wolfe 1998, Altieri 1999) in crops such as such as leeks (Baumann ef al. 2001) and carrots (Brandsseter and Riley 2002). 

Conventional breeders often think that organic farmers require an absolute disease resistance, but in many cases tolerance or partial resistance can be sufficient. Organic farmers are used to searching for ways to reduce risks by an array of solutions at different levels (farm, crop, variety) and also adopt such a strategy in their search for appropriate combinations of supporting variety characteristics. There are different variety characteristics that support yield and yield stability through optimal plant health (Table 5.2). Plant health can be defined as a result of the following components ... 

Balfour summarizes some of the far-reaching claims made by many advocates of humus farming. They are that if the fertility of the soil is built up with adequate supplies of humus, crops do not suffer from diseases and do not require poison sprays to control parasites that animals fed on these plants develop a high degree of disease resistance, and that man, nurtured with such plants and animals can reach a standard of health, and a power of resisting disease and infection, from whatever cause, greatly in advance of anything ordinarily found in this country. It would indeed be fortunate if this quotation were fact rather than fallacy. 

Types of dark-brown or black granular muck have produced large quantities of vegetable crops and are often used for grain production and stock farming. Fertilizers, especially potash, can be used profitably. Rotations with oats and rye are common when the principal crops, such as onions, celery, and cabbage are threatened with insects and plant diseases. The production of reed and sedge peat and muck for soil improvement is of commercial importance in this area. 

Quy, R.J., Cowan, D.P., Haynes, P., Inglis, I.R. Swinney, T. 1992. The influence of stored food on the effectiveness of farm rat control. Proc. Br. Crop Prot. Conf. - Pests and Diseases, pp. 291—300. Thornton Heath British Crop Protection Council. 

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