Integrated management of fusarrium wilt-root knot nematode complex on tomato in central highlands of Kenya
Wanjohi, Waceke J.
Wafula, Geoffrey O.
Macharia, Charles M.
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Tomato plays a critical role in meeting nutritional food requirements, generating income and creating employment for both the rural and urban populations in Kenya. However, its production is threatened by the Fusarium wilt caused by Fusarium oxysporum f.sp. lycopersici, root knot nematodes (Meloidogyne spp), Fusarium wilt-root-knot nematode complex and Tomato leaf miner (Tuta absoluta) among others. Yield losses of 80-100% in some instances, have been reported due to the Fusarium wilt - root knot nematode complex. Field experiments were set up in two sites (Kagio and Mwea) in Kirinyaga County in Central highlands of Kenya to evaluate the effectiveness of various Integrated Pest Management (IPM) packages for the management of fusarium wilt-root knot nematode disease complex in tomatoes. The trials were established in two seasons, the long rains (March – July 2016) and the short rains (September 2016- January 2017). The IPM packages tested were NatuGro system (a combination of soil improvers, plant biostimulants and Trichoderma harzianum T22), a fungicide (carbendazim), Nemix (Bacillus sp. based biocontrol agent) and bionematicide (Paecilomyces lilacinus T251) applied either singly or in combination. Root knot nematode (RKN) gall index, as a measure of nematode disease severity was assessed twice during the experimental period; at flowering and mid fruit stage, while severity of fusarium wilt was assessed using the vascular wilt rating scale of 0-5. Fusarium wilt incidence was evaluated biweekly from 2 weeks after transplanting by visual assessment of wilt symptoms and expressing them as a percentage of total number of plants per plot. Both total and marketable tomato yields were determined at the end of the experimental period (4 months after transplanting). Integrating NatuGro system, Carbendazim and P. lilacinus was most effective in reducing RKN disease severity and damage and improving tomato growth followed by NatuGro system applied singly. Fusarium wilt severity and incidence were low throughout the experimental period and in all the treatments in both experimental sites. Keywords: Paecilomyces lilacinus, carbendazim, NatuGro system, Nemix, Venishine, NoPath and Trichoderma harzianum T22