Calcium chlorate, a cotton defoliant
1994
Rimon, D.
A new product belonging to the Chlorate group was tested in order to improve the defoliant performance for preparation of cotton fields for harvesting. Calcium Chlorate was compared, in field trials at the Bet-Dagan farm, Israel, in 1992 and 1993, to "Mg-18" Mg (ClO3)2 18 and "Drop-Ultra" (Thidiazuron, 120 g/1). The varieties, Acala SJ2 and Sivon, were grown under a complete irrigation regime. The two chlorates were more efficient than Drop-Ultra, although the last one inhibited leaf renewal, at least in the apex, until the end of observations in all the experiments. The efficiency of Calcium Chlorate as a defoliant agent has been proved both in experiments performed early in the season, at the beginning of September and, later on, at the end of September/beginning of October. The quality of defoliation was determined by two complementing methods:the first, a visual method by qualitatively grading the appearance of the treated plots. The second, a more objective method, in which all leaves, dry or fresh, remaining on plants, were collected following treatment and replication from a representative row in the middle of the plot. The leaves from the plot were dried in an oven and weighed. The main findings indicated that Calcium-Chlorate was somewhat better than Magnesium Chlorate. Chlorates were more efficient than Drop-Ultra in defoliation though not in preventing leaf renewal. When minimal temperatures dropped, close to the physiological limit of 16 degrees Celsuis, the performance of the Chlorates was sustained. If the harvesting schedule matches the defoliation plan it is possible to harvest, within a period of 6 to 10 days, after a second spraying, with minimal leaf renewal, at least in those fields which are physiologically prepared.
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