Sitophilus zeamais (Motsch.) is an important storage pest of maize grain in several parts of Africa including Zimbabwe. Although synthetic pesticides are effective at controlling the pest, environmental and health hazards of these chemicals are of increasing concern. The study assessed efficacy of botanical leaf powders of Eucalyptus tereticornis, Tagetes minuta and Carica papaya in controlling S. zeamais using rates of 5 g, 10 g and 20 g per 200 g of open pollinated maize grain (variety ZM421). The trial was laid in a completely randomised design (CRD), with 12 treatments replicated three times. The grain was put in a freezer at-4 o C for a fortnight, before the botanicals were added, to kill any prior sources of weevil inoculum and eggs which might be already pre-existing in the grain. 200 g maize grain was infested with 200 three week old unsexed pure culture weevils in 750 ml jars. After 14, 28, 42, 56 and 70 days, weevils were sieved and their mortality determined. Percentage grain weight loss was assessed after 35 days post pests introduction. There were significant differences (p<0.05) in number of weevil mortality and grain weight loss among treatments and their application rates. The findings showed that conventional chemical control was most effective than all botanicals used. E. tereticornis was the most effective of all the botanical pesticides at an application rate of 20 g as evidenced by high weevil mortality and less grain weight loss. It was concluded that botanicals have storage pesticidal properties to suppress S. zeamais in maize grain and could be used as an alternative control option to synthetic pesticides.

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Cotton yield and fibre quality parameters are dependent on the environment in which the crop is grown. A major challenge in crop genotype recommendations is genotype × environment interaction. The identification of cultivars with high adaptability and stability is one of the best ways to address this challenge. Genotype × Environmental interaction on Gosypium hirsutum was investigated. Ten genotypes were planted in a randomised complete block design with three replications. Collected data were subjected to Analysis of Variance (ANOVA) with genotype and location as factors. Additive Main Effect and Multiplicative Interaction model which combines standard analysis of variance with principal component analysis was used to investigate the genotype main effects, environment main effects and the GE interactions. Significant genotype × environment interactions existed for lint yield, boll weights, staple length, and fuzzy seed grade. There were no significant cultivar × site interactions on total seed cotton yield. Cotton cultivars respond differently to different growing conditions implying that, correct choice of varieties by growers for specific production conditions, must be a must to avoid losses due to genotype × environment interactions.

Radopholus similis is the most destructive plant parasitic nematode in banana production systems. A glasshouse experiment was carried out to evaluate the effect of legume intercrops on R. similis population and damage level in banana. A trial was laid out in a randomised complete block design with five treatments and five replications. The treatments were banana/cowpea (Vigna unguiculata) intercrop, banana/sunn hemp (Crotalaria juncea) intercrop, sole banana, sole banana with nematicide (Fenamiphos) and sole cowpea. Sunn hemp intercrop was suppressing R. similis population densities and reduced banana root damage the most compared to tested treatments. The legume intercropped banana plants had a significantly higher fresh root mass as the sole-cropped banana with nematicide while the solecropped banana without nematicide had significantly lowest fresh root mass. Sunn hemp and cowpea legumes are recommended for adoption by smallholder banana farmers as alternatives to nematicide use.

Okra (Abelmoschus esculentus L.) is one of the horticultural crops commonly grown in Zimbabwe but the productivity of the crop is hampered by poor erratic seed germination due to dormancy. A study was carried out at Bindura University of Science Education to determine the best method and treatment combination of breaking okra seed dormancy. Viability tests and germination tests were conducted first to ascertain that failure of germination was due to dormancy. The study consisted of 3 laboratory experiments arranged as factorial treatment structure laid in a completely randomised design with 3 replications. The 3 experiments consisted of 3 methods of breaking seed dormancy (water soaking, acid scarification and dry heating). Each of the different methods was employed at different exposure duration and at different temperature/concentration levels. Germination was measured for 14 days to determine the total final percentage seed germination. Acid scarified seeds for 3 min at 80% H 2 SO 4 concentration level had the best germination percentage of 96.6% followed by dry heating for 5 minutes at 70°C and soaking for 12 h at 30°C which had 92.2 and 91.3% germination respectively. However, H 2 SO 4 scarification for 5 min at 60% concentration gave the least germination of 44% followed by soaking for 48 h at 30°C and dry heating for 5 min at 80°C which all resulted in 50% germination. Based on the research findings, 80% H 2 SO 4 for 3 min can be used by okra farmers to break dormancy while dry heating for 5 min at 70°C and soaking for 12 h at 30°C are equally good alternatives.