Journal de pathologie végétale et de microbiologie

Abstrait

Fungicidal Management of Garlic Rust (Puccinia allii) and Assessment of Yield Losses Due to the Disease

Tilahun Negash, Hassen Shifa and Tefera Regassa

Garlic rust which is caused by Puccinia allii is the most common and economically important foliar disease. Assessing the relationship between rust and yield loss of a given disease on a specific crop serves to know the effect of a given disease on specific crop directly on it yield. The objective of this study was to manage garlic rust through fungicide, and determine the extent of yield losses. Field experiments were conducted to evaluate the
effects of systemic fungicide (Natura) spray at rates (0.25, 0.5, and 0.75 L/ha) and frequencies of application (7, 14, 21, 28 days) with unsprayed control. The treatments were tested for their effects on severity and yield and yield components of garlic. The field experiment fungicide treatments were depicted different severity levels that resulted in different garlic yield losses. The final levels of severity were about 89.9% at MWRRS and 87.2% at SARC. The different disease severity levels created by different fungicide spray frequencies and rates caused different amount of losses in total yield. The highest relative total garlic bulb yield loss of 54.26% and 48.30% was occurred at MWURRS and SARC, respectively when plots were left unsprayed. Linear regression of the AUDPC was used for predicting the yield loss in garlic due to rust. The estimates indicated that -0.15, -0.098, and -0.091t/ha yield losses were predicted on 0.25 L/ha, 0.5 L/ha, and 0.75 L/ha, respectively for every % of days increase of AUDPC at MWURS. Similarly at SARC, the estimated slopes were b1=-0.104, -0.090 and -0.086 on 0.25 L/ha, 0.5 L/ha, and 0.75 L/ha, respectively. However, from this finding, use of Natura fungicide at rate of 0.75 L/ha within 14 days spray interval was found to be effective management option. Since the study was first hand exercise similar study need to be conducted using more number of location and seasons.