The whitefly, Bemisia tabaci, is the main pest for many field and horticultural crops, causing main and significant problems. The efficiency of imidacloprid insecticide as seed treatment and foliar spray at three rates against the whitefly, B. tabaci, was evaluated in tomato plants under field conditions; in addition, insecticide residues were determined in tomato leaves and fruits. The obtained results revealed that the seedlings produced from treated seeds with imidacloprid were the most effective treatment in decreasing whitefly stages. Reduction percentages of whitefly stages in seedlings produced from treated seeds and sprayed with ½, ¾ and 1 field rates of imidacloprid were more than that produced from untreated seeds. Tomato fruit yield in seedlings produced from treated seeds and sprayed with one recommended rate of imidacloprid was more than that of untreated seeds. The residues of imidacloprid in leaves and fruits in seedlings produced from treated seeds and sprayed with field rate were more than that of untreated seeds; additionally, the residues were higher in leaves than in fruits. The residual level in fruits was less than the maximum residual level (MRL = 1 mg kg−1) of the Codex Alimentarius Commission. The half-life (t ½) was 6.99 and 6.48 days for leaves and fruits of seedlings produced from treated seeds and 5.59 and 4.59 days for untreated seeds. Residues in tomato fruits were less than the MRL, therefore, imidacloprid is considered an unconventional insecticide appropriate for B. tabaci control that could be safe for the environment.

Whitefly, Bemisia tabaci cause important losses for many crops especially tomato, therefore farmers often use many chemical insecticides which had dangerous side effects on human beings and environment, thus there are need to determine the residues of these chemicals in plant . The dissipation of thiamethoxam in tomato leaves and fruits followed the first order kinetics; Half-lives were 2.91 and 3.15 days for fruits and leaves, respectively. The residues of thiamethoxam were determined using a QuEChERS method with HPLC-DAD and it was 0.14 mg/ kg in fruits after 7 days of treatment and less than the maximum residue limit (MRL 0.2 mg/kg. The residue in leaves was more than in fruits. Seedlings produced from treated seeds were more resistant to different stages of the whitefly population and protect tomato plants from whitefly infestation for 6-10 weeks after transplanting. The three sprays of thiamethoxam increased the reduction percentage of B. tabaci stages and the highest increase was recorded after the third spray in egg, nymph, and adult stages. It could be recommend that Thiamethoxam is considered an unconventional insecticide appropriate for B. tabaci control and safe for humans and the environment.

Effect of two fungicides (i.e. iprodione and cyprodinil+flydioxonil mixture) and two salts (sodium bicarbonate, SBC, and sodium benzoate, SBO) were evaluated separately or in mixtures in laboratory experiments as well as under field conditions against Botrytis cinerea instant of the fruit gray mould of strawberry. All tested salts and fungicides as well as their mixtures significantly decreased the radial growth of B. cinerea in vitro. Complete inhibition of radial growth was obtained with SBC at 2.0 and1.0 g/100ml. Also, high reductions were obtained with SBC at lower concentrations. The fungicide iprodione at 500 mg/L completely inhibited radial growth of B. cinerea, while complete inhibition was obtained with cyprodinil+flydioxonil at lower concentration (10 mg/L). Mixing the tested fungicides with salts increased their inhibition effect on B. cinerea growth at lower fungicide concentrations. iprodione at 0.1 mg/L mixed with SBO at 1g/100ml completely inhibited radial growth. Also, cyprodinil+flydioxonil at 0.1mg/L mixed with SBC at 0.2 g/100ml completely inhibited radial growth of B. cinerea while 0.001mg/L cyprodinil+flydioxonil fungicide with SBO at 2.0g/100 completely inhibited radial growth. On the other hand, the field experiments showed that all treatments with the tested salts and fungicides significantly decreased postharvest Botrytis gray mould on fruits harvested 1, 3, 7, 10 and 15 days after treatments and stored at 5˚C for seven days. However, the treatment with 50% cyprodinil+flydioxonil + SBC 2% was the most effective and decreased mean percentage of infection to 4% compared to 23.86 % for the untreated control. This was followed by 50% iprodione +SBC 2%, 25% iprodione + SBC and 25% cyprodinil+flydioxonil + SBC 2%, and cyprodinil+flydioxonil, alone, and iprodione, alone, with percentages of infection being 7%, 8%, 8.5%, 8.5%, and 9%, respectively, while (SBC 2%, alone) treatment showed the least effect with 12.93 percentage of infection. Meanwhile, positive strong correlations (r = 0.981 to 0.943) were revealed between Infection (%) and harvest interval periods with two salts mixed with iprodione and cyprodinil + flydioxonil after stored at 5˚C. Also, the enzyme assay revealed that increases in the activity levels of pectolytic and cellulytic enzymes produced by the fungus were associated with high fruit rots incited by B. cinerea. Meanwhile, residues of all tested fungicides in treated strawberry fruits decreased with decreasing fungicide concentrations in the salt + fungicide mixtures. cyprodinil (25%) + SBO, and cyprodinil (25%) + SBC treatments exhibited the lowest residue values being 1.420, and 1.680 mg/kg fruit one hour after treatment while the other treatments showed higher residue values while the highest was recorded for iprodion at recommend dose being 29.81 mg/kg fruit. However, fungicide residues decreased with increasing time after preharvest treatments.