Effect of planting dates and recommended insecticides application on Earias insulana (Boisd.) and its associated predators in cotton field in Egypt

Abstract

Cotton crops are an important agricultural product in Egypt. However, the bollworm Earias insulana is a significant pest of cotton. Field experiment was carried out during the 2018 and 2019 seasons at Qaha Experimental Station, Qalyoubia governorate to determine the best dates for sowing cotton crops, to minimize E. insulana infestation and maintain high populations of the predators of spiny bollworm. The latest sowing date had a significantly lower infestation of squares, flowers and green bolls than the other two sowing dates. After spraying the three planting date plots with profenofos, lambda-cyhalothrin and methomyl insecticides, infestation of cotton bolls by spiny bollworm was significantly reduced in treated compared with untreated plots. A significant positive correlation (r = 0.829* and 0.827*) was found between the average temperature and E. insulana infestation of squares and flowers, respectively, for the first planting date and (r = 0.819*) in squares for the second planting date of untreated plots of season 2018. The explained variance percentages of multiple regression analysis showed that the effects of mean temperature and relative humidity (RH) on the third sowing date had a significantly lower infestation of squares, flowers and green bolls by spiny bollworm as compared to the first and second sowing dates. The populations of common natural enemies of E. insulana on cotton plants, i.e., Chrysoperla carnea, Coccinella undecimpunctata and spiders were counted during the two seasons. The correlation between the RH percentage and populations of the three predators was insignificantly positive during the 2018 season, while it was negatively or positively insignificant during the 2019 season. The correlation between the mean temperature and the populations of the three predators was insignificantly negative for C. carnea and positive for spiders during the 2018 season, whereas a positive correlation was found between temperature and C. carnea and spiders and a negative correlation between temperature and C. undecimpunctata during the 2019 season.

Effect on Cotton Growth and Quality Under Different Climatic Conditions of Pakistan

“…Many scientists concluded that even a delay of week in sowing may result in a marked decrease in yield. Khan and Gill 1982;Qayyum et al, 1990;Ansari et al, 1991;Arain et al, 2001;Moustafa 2022 andZhang et al, 2022, reported that early sown cotton (15 April to 15 May) gave significantly higher plant height, number of sympodial branches, number of bolls formed, seed cotton weight per plant and seed cotton yield per hectare. Khan et al, 1981;Ansari et al, 1989;Soomro et al, 2000;Kakar et al, 2012 andKeerio et al, 2022 observed that 15 th May is an optimum sown crop gave increased number of bolls per plant, boll weight and seed cotton yield per hectare and they further noticed a remarkable decline in the yield of late sown crop.…”