Parawilt in Cotton
Authors: Raghuveer Singh, Roshan Lal Meena, Pradeep Kumar and Raman Sharma
Among the different physiological disorders in cotton like leaf reddening, parawilt/new wilt, leaf drying, bud and boll drying, bad boll opening, crazy top, crinkle leaf, effect of 2,4-D, bud and boll shedding and mineral nutrient deficiency/toxicity (Perumal et al., n. d). Parawilt is most threatening the cotton farmers and cause of big loss with the introduction of Bt-cotton varieties. It is not an associated disorder of Bt-cotton but there higher production level is reason behind that it is one of the major problems of Bt-cotton varieties. Our farmers cant get that why there crop suddenly die even though everything suitable for the crop even some time the extension workers and field person also get confuse with symptom of parawilt and they suppose that its any disease outbreak.
Sudden/Parawilt it is a common term which are used when plant suddenly dies at flowering and fruit filling stage. Parawilt mainly occur due to the sudden imbalance between the water demand of plant and its supply. It is totally different from the normal wilting which are due to lack of moisture that is a gradual process and easy to control but in case of parawilt plant die suddenly due to excessive water. Due to excessive water un aerobic condition creates and oxygen supply to the plant root gets checked. Whatever oxygen available in the root zone consumed by the micro-organism within few hours of the rain and plant roots gets choked. Because of respiration process of plant roots stopped plant unable to take water even though no deficiency of water in the root zone.
Sudden rainfall or apply the excess water to the crops through irrigation supported by the poor soil condition, rapid growth of plant at grand growth stage and bright sunshine/hot air temperature initiated the sudden wilting. It is soil-pant-atmosphere continuum related issue. The sudden wilt in cotton is characterized by a premature death of top leaves followed by collapse of the plant. Wilting of leaves can be seen within a few hour of rainfall or soil saturation (Hebbar and Mayee, 2011). Due to parawilt plant get die within few hours of rainfall and it look like that field burn due to wild fire. Wilted plants eventually shed all their leaves and are left with small immature fruits. If parawilt occurs just prior to harvest, bolls may forcefully open but will not ripen fully, leading to poor quantity and unmarketable quality (Hebbar and Mayee, 2011).
It’s difficult to control the parawilt because it have several reason overr-watering, lack of water, too much sun, not enough sun, too many/much fertilizers, diseases caused by infection, etc. Only we need to teach our farmers that how they can avoid wilting and one thing once plant get wilted its impossible to recover except some case in early stage but that also face heavy reduction in the overall yield. Hebbar and Mayee, 2011 suggested some points by which farmers are can avoid parawilting
Farmers should avoid the application of excess water because it cause development of roots at the surface level and chances of parawilt increase if farmers apply heavy irrigation at the time of flowering or occurrences of rains followed by bright sunny day with hot air temperature
Parawilting mainly faced by the ill drained soil like as the clayey or salty soil so if farmers go for cotton cultivation in such soil he must insure that proper drainage facility is there in the field
Choice of cultivars
Researchers found that G. arboreum and G. herbaceum are more resistant compared to G. hirsustum so we can suggested to farmers to for desi cotton in place American cotton if soil condition are not support to it
Optimum vegetative growth of the crop
Farmers should avoid the application of excessive fram yard manure and fertilizers to the crop which will cause the excessive vegetative growth of plant chances of wilting in the later adverse condition. As much as surface area plant loss more water through evapo-transpiraton and if condition are not supportive than chances of wilting get increase
Perumal NK, Hebbar KB, Rao MRK, Singh P (n. d.) Physiological disorders in cotton, CIRC technical bulletin No:-28. Accessed on December 24, 2017, http://www.cicr.org.in/pdf/physiological_disorder.pdf
Hebbar KB, and Mayee CD (2011) Parawilt/sudden wilt of cotton - a perspective on the cause and its management under field condition, Current Science 100 (11) 1654-62.
About Author / Additional Info:
I am working as a scientist at ICAR-IIFSR, Modipuram, Meerut, Uttar Pradesh, India.