Abstract: The classification, damage loss and control strategy were studied for cotton boll rots in Shanxi province. Results showed that the main kinds of cotton boll rots included boll blight(Phytophthora boehmriae), rose rot(Fusarium moniliforme) and pink rot(Cephalothecium roseum), and boll blight was the dominant species. Comparison revealed that boll rot in the film-mulched field was more severe than that in the open field. The results of Bayes decision analysis indicated that 67.4-89.1% of the secondarily-affected boll population originated from the prima’rily-affected bolls, especially those affected by boll blight. Significace tests indicated the vertical distribution of the affected bolls on the branches consisted of 2 strata, i. e. the first to the fourth boll-branch stratum and the 5th to the 7th boll-branch stratum for the film-mulched field, and the first to the second boll-branch stratum and the 3rd to the 6th boll-branch stratum for the open field. The quantitative relationship between the primary and the secondary pathogenetic fungi infections was clarified, and the main objects and target areas were defined for boll rot control. These results provided a theoretical basis for the integrated control of cotton boll rots.

Key words: Cotton, Boll rot, Damage loss, Control strategy