Abstract
Diamondback Moth (DBM) is one of the major constraints for the profitable production of cabbage in the country as well as Ambo highlands in particular. The field study was conducted to evaluate the susceptible varietal resistance of cabbage ( Brassica oleracea var.capitata) against diamondback moth (DBM) ( Plutella xylostella ) infestations and damages at the Ambo university farm in a relay cropping (Rain season) in 2019. Varietal resistance was compared with conventional spraying using Randomized complete block design (RCBD) spraying chemical of insecticides at different spray interval. The Cabbage varieties were Copenhagen from local market. Sampling was done by weekly counting of larvae and pupae, and scoring pest damage on six randomly selected plants per plot for 5 weeks from the third week after transplanting. The number of damage and undamaged cabbage heads were counted on all plants per plot at maturity stage. Results showed that sprayed and unsprayed plots had significantly (P<0.05) different numbers of DBM stages (larvae and pupae). The yield losses of cabbage caused by DBM could reach up to more than 80% as several infestations occurred in the field. Due to this problem, farmers in Ambo highlands are preferred to apply the broad spectrum of non-systematic insecticides rather than implementing other pest management strategies. The demand for insecticides in Ambo highlands seems endless until today, but more aggressive. This paper highlighted the possibility of implementing intercropping cabbage with six treatments in reducing pupae and larvae populations of DBM in the polyculture system. The distributions of pupae and larvae population of DBM against the factors of temperature and rainfall also have been addressed in this study. A total of six treatments were indicated, that including Cutter, Trigger, Ethiozenon, Nomax, Fastac and Control which arranged in (RCBD). The result indicated that nonsignificant variations (P<0.05) were observed among the population of pupae and larvae at all seven treatments tested compared with the control. Moreover, pupae and larvae of DBM were negatively correlated with temperature and rainfall factors. The results also showed that a critical period of DBM infestations was detected in the pre-heading stage (< 30 DAT). In terms of performance among treatments, our finding also has shown that Nomax was the best treatment acted as a repellent. Keywords: Diamondback Moth, Management Strategies, (Plutella xylostella ) Insecticide Resistance. DOI: 10.7176/JBAH/11-23-04 Publication date: December 31 st 2021
Highlights
Cabbage, both head and kale, is the second most important vegetable crop in Ethiopia both in area coverage and as well as level of production next to red pepper, Capsicum spp. (Moa 2002)
Result and Discussion Effects of Insecticide Application on Diamondback Moth (DBM) The different insecticides were sprayed to respective plots sown cabbage at every seven days interval so that to evaluate the effectiveness of each insecticide against DBM as follows; Cutter (Emamectin benzoate 48gm/lt+Acetamipride 64gm/lt), Trigger (Lambda Cyhalothrin (50g/ltEC), Fastac, Nomax (Teflubenzuron (150Sc) and Ethio-zinon (Diazinon (600gm/l) consecutively
The chemicals were formulated based on the recommendation written down on the containers of each pesticide by the Companies
Summary
Both head and kale, is the second most important vegetable crop in Ethiopia both in area coverage and as well as level of production next to red pepper, Capsicum spp. (Moa 2002). Both head and kale, is the second most important vegetable crop in Ethiopia both in area coverage and as well as level of production next to red pepper, Capsicum spp. The area of oilseed rape planted increased by 59%, and in 2009 more than 31 million hectares were cultivated worldwide (FAOSTAT, 2012), often in regions where the crop was not previously grown. These changes have resulted in considerable modifications to many local landscapes (Furlong et al, 2008) and provide revised challenges for DBM management (Schell horn et al, 2008)
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