Evaluation of Napier grass cultivars for resistance to Napier head smut

Abstract

Napier grass (pennisetum Purpureum) is a tall, perennial grass that is indigenous to tropical Africa. Napier grass diseases are rare but napier head smut disease was reported in Kenya in the early 1990s and was reported to cause reduction of biomass up to 46%. The objective of the study was to evaluate for resistant cultivars. Seven napier grass varieties were evaluated for resistance to napier grass smut disease ( Ustilago kameruniensis ) in a greenhouse at KARI Muguga South. The varieties were Kakamega I (resistant control); Kakamega II, Muguga bana and Ex-githunguri and three susceptible controls (clone 13, farmer bana and French Cameroon). The results affirmed the resistance of Kakamega I and clone 13 was resistant. Among the test cultivars, Kakamega II was highly resistant whereas Ex-githunguri and Muguga bana were susceptible (disease rating 7.1% and 3.6% respectively) after 42 weeks. French Cameroon and Farmer bana were highly susceptible (disease rating 18.2% and 50% respectively). Fr ench Cameroon was most prolific in tillering with 6.9, 15 and 23.3 mean tillers at 8, 16 and 24 weeks after planting. Ex-Githunguri had the least number of tillers with an average of 3.3, 3.4 and 4.4 tillers for the respective time intervals. Farmer bana had the highest Leaf:stem ratio (6.06) while Kakamega I had the least (1.65) for non-smutted material. For smutted material, Ex-githunguri had the least of 1.01 and French Cameroon the highest of 2.89. The identified resistant cultivars should be disseminated to the farmers to ameliorate the smut problem as more resistant and productive varieties are evaluated to diversify germplasm at farm level as a precautionary step to mitigate potential future infections that are currently not there.