Experiments were carried out at Aghour region, Qalubia Governorate,  during two successive years 2002 and 2003. Mixture of some chelated microelements (Zn 12 %, Mn 12 % and Fe 12%), a plant growth promoter namely Easterna super biofert (N 6%, P2O5 4%, K2 O 8%, Zn 500 p.p.m., Fe 1000 p.p.m., Mn 250 p.p.m., Cu 100 p.p.m., Mg 1%, carbohydrates 6% and amino acids 10%) a mixture of both materials were used in field trials to study the effect of such treatments on cotton plants and rates of infestation with bollworms. The treatments were microelements (400 gm. / feddan), plant growth promoter (400 cm3 / feddan) and their mixture, at the same rates. All treatments, which were, applied 45 and 60 days after sowing caused earliness in the first opening boll comparing with control. Mixture treatment was the most effective one, induced an earliness by 13.04 and 13.77 % and the highest   ratios of opened bolls by 81.62 and 86.61 % showing increases by 37.38 and 42.17 % in 2002 and 2003 cotton seasons, respectively. Such treatments induced % reductions in bolls infestation with P. gossypilla and E. insulana by 10.64, 28.68 and 31.66 % in 2002 and by 13.76, 24.82 and 31.75 % in 2003 for the three treatments, respectively.  Reduction percentages of infestation   reflected finally in decreasing  the yield loss. Treatments could be arranged according to their efficacy as follows: mixture was the highest followed by plant growth promotor treatment and finally      the microelement treatment. Mixture proved to be a good nutritive to cotton plants  and decreased the bollworms infestation rates.