Cian 95 and Cian Precoz, two new varieties for the northern of Mexico, requiere close attention to harvest management to avoid problems with insects pests at the next season. Also, these cultivars respond to harvest aids chemicals differently from Delta type varieties. The objective of this study was to evaluate the response of Cian 95 and Cian Precoz to defoliation. The experiment was established during 1992 at the Experimental Station at La Laguna, Mexico. The experimental design was a split plot with four replications. Main plots were defoliation dates: 1) For Cian 95 at 126, 129, 131, and 133 days after planting and 2) for Cian Precoz at 118, 129, 122, and 124 days after planting. Sub plots were defoliants: 1) Untreated check, 2) Defolia, 3) Dropp, and 4) Dropp+Karmex. Data were taken in leaves number and dry matter at 7 and 21 days after application.

In both cultivars, Dropp and Dropp + Karmex caused the most consistent defoliation. Defolia did not produce any effects on Cian Precoz. On the other hand, Defolia showed a 13 percent less defoliation than the best treatments. There were not significant differences on defoliation dates.