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Controlling Bacterial and Fungal Diseases in Crops: Farmers' Wisdom (Part - I) Traditional methods of plant protection have largely been ignored in controlling bacterial and fungal diseases. Although, chemical control methods are more popular for providing quick solutions, these are not sustainable. Many farmers have effectively controlled and prevented occurrence or diffusion of diseases by following simple innovative practices. This synthesis mainly comprises the innovations published in Honey Bee during the last eleven years and some of the traditional knowledge gleaned from internet. This has been compiled by Shreshta Sarkar and other members of SRISTI. Rust causing fungi affect mainly Graminaceous crop species in all the stages of their development. Rusty pustules appear on leaf sheath during early stages of disease that spread on the ears with further development and finally affecting the entire spike. Smut causing fungi also infect members of gramineae where the pathogen causes devastation at the grain formation stage converting the grains into black powdery mass. Two types of mildews are found- powdery and downy. They are classified on the basis of the causal fungi, infecting the cucurbits and solanaceous plants in addition to gramineae family. In powdery mildew, lesions appear on the leaves as powdery patches causing early decay, which in turn affects the development and the yield (Mehrothra, 1992). Wilting, in crops is caused by both bacteria and fungi. The affected plants show gradual loss in vigor and ultimately die-off (Mehrothra, 1992). Blight disease is characterised by the appearance of lesions on the leaf in case of both bacterial and fungal pathogens. Similarly, both bacterial and fungal rotting show similar symptoms as softening and decomposition of plant parts infected by the causal pathogen. Damping- off disease of either bacterial or fungal origin occurs at the seedling stage, causing decay of the seedling, which drastically affects its further growth. Diseases of Wheat Rust: Both wheat leaf rust (c.o. Puccinia recondita f.sp. tritici) and wheat stripe rust (c.o. Puccinia striiformis f.sp. tritici) are caused by fungal pathogens. Due to the longer viability of pathogen spores and wide-range dissemination by wind, most control measures are ineffective. Crop rotation and avoidance of environmental factors favourable for the pathogens are the prevailing cultural control methods [www.ento.ok.state.edu/ddd/disease/wheat leaf rust.htm]. Traditional practices involving seed treatment, irrigation procedure and use of traditional fungicides are employed to Traditional methods of plant protection have largely been ignored in controlling bacterial and fungal diseases.
arrest the pathogen activity. Farmers immerse seed of wheat in milk before sowing to avoid rust disease [Madhanbhai Bikhabhai Solanki, Rajkot, Comm: Rathod Balvantsinh P, HB, 2(1): 18,1991]. Use of milk for controlling plant diseases has been known for a long time [See HB 3(3&4): 8, 1992, HB 4(2&3): 20, 1993, HB 9(3): 14, 1998, HB 10(1): 14, 1999, HB 10(4): 14, 1999 for use of milk in controlling plant diseases]. It has been found that, "milk with its natural enzymes and simple sugar structures, can be used to combat various mildews on cucumber, asters, tomato, squash and zinnia foliage. A 50/50 mixture of milk and water is recommended. Plants are thoroughly sprayed with the milk-water mixture every three to four days at the first sign symptoms of mildews or later use as a preventative measure" [www. ghorganics.com/page15.html#Milk For Mildew]. The crop is irrigated less and that too at night to control rust.[Karhanbhai Karambhai Desai, Banaskantha, Comm: Manaji V Thakore, HB, 2(1): 17,1991]. A drip irrigation system is recommended to avoid wetting the foliage. Wet foliage promotes fungal diseases [www.sunone.com/ news/articles/03-07g.html].
During the spike formation stage, bones of camel are buried in the irrigation channel. This is believed to control rust within 10-15 days [Kodarsingh T Zala, Sabarkantha, Comm: Rajendrasingh G Zala, HB, 5(1): 20,1994]. In addition, mulching has been used in a cultural control measure, "a layer of two to three inches of porous mulch like straw or leaves is kept over the soil. This keeps the soil temperature even. It also prevents soil-borne fungal pathogen spores from being splashed on the foliage and fruit when it rains or during irrigation " [www.sunone.com/news/articles/03-07g.html]. Diseases of Rice Rice plant is affected by various pathogens both fungal and bacterial during all stages of its development. |
