A field experiment was conducted in vertisols in varying rainfall patterns during 2013, 2014 seasons at ICAR-Central Institute for Cotton Research farm, Nagpur. The main objective of this study was to advice the farmers in varying rainfall patterns on reduce their weed management cost through early post emergence graminicides. Farmers should carefully follow weather CICR weather advisory on cotton cultivation a weekly web bulletin. In a year of weak monsoon farmers should go for direct sowing of cotton whenever 60 mm rainfall is received without any pre emergence residual herbicide application as it does not work in desiccating weather conditions under seedling droughts. The year may begin with very good pre monsoon rains farmers have only one option glyphosate @1.0 kg a.i. ha-1 as PPF application on emerged weeds before or within three days after planting of cotton or before cotton seedling emergence. The year might have began with very good monsoon followed by weakened monsoon with late seedling drought where normal interculture operations can take care of weeds and conserve soil moisture followed by limited hand weeding with available family/hired labour. However, revival of monsoon with continuous heavy rains farmers can use early post emergence application of propaquizafop on 3-4 weeks old grassy weeds or pyrithiobac sodium against broad leaf weeds or a tank mixture on clear sunny day for atleast 3-4 hrs. In case of late active continuous monsoon rains after squaring stage of cotton young weeds are difficult to be removed by intercultural operations or hand weeding operations if allowed to grown consume all the top dressed urea. Therefore, farmers may use glyphosate 2 ml directed spray 2 and 4 ml L against grasses and broad leaf weed control respectively as layby directed application. Cyanotis auxillaris, Commelina benghalensis and Digera arvensis were effectively controlled by Pyrithiobac sodium 1.8 ml L-1 or glyphosate 2 ml L-1. Commelina benghalesis was effectively controlled by both quizalofop-ethyl and fenoxoprop-methyl. Yellowing and stunted growth of cotton was observed with all the post emergence herbicides application compared to farmer’s practice. Validation trials in farmers field’s observed the yellowing was recovered by a fortnight later but farmers are forcibly using PGRs to fasten the early seedling growth, which is increasing the cost of cultivation by US $ 400 ha-1.

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