Evaluation of maize introductions for resistance to turcicum leaf blight, maize streak virus disease and tropical maize rust in Uganda

Abstract

In the tropics, turcicum leaf blight (TL.B) (Exserohilun turcicum), maize streak gemini virus disease (MSVD), and tropical maize rust (Puccinia polysora) are endemic and the most important maize foliar diseases in many countries. Thus deployment of varieties with multiple resistance to these diseases is key in increasing production. This study evaluated the disease reactions of elite Ugandan varieties and Pioneer hybrid introductions by considering the rate of disease increase (r), intercept or initial amount of inoculum (Yo*), area under disease progress curve (AUDPC), lesion numbers and percentage leaf area blighted. Significant differences in susceptibility of Ugandan varieties (P<=0.05) to TLB blight were observed. Population 28 was most susceptible while Babungo 3 was most resistant. Regression analysis revealed a linear relationship between yield and turcicum leaf blight severity (R² = 0.50**), but there was no significant difference (P 20.05) in yield of Ugandan elite varieties. No significant differences were observed among Pioneer hybrids in susceptibility to all the three diseases and they were in general, considered resistant to all the three diseases and comparable to the elite Ugandan varieties. Epidemiological models and their resultant disease indices fitted to TLB and rust disease progress distinguished between the various varieties studied.