A Comparison of Blight Infection Rates in Four Walnut Cultivars as Affected by Spray Treatment and Environment
Walnut blight is a major disease decreasing yield worldwide.There are few treatment options with the most common being copper sprays, often with the addition of Mancozeb(R) as an adjuvant.This study measured infection on the developing nuts of four cultivars mid-growing season in two years in an irrigated orchard in south-western Victoria, Australia.Comparisons were made between copper/Mancozeb(R) treatments and unsprayed control trees in 2011.In 2012, a third treatment was added, a biological spray containing beneficial bacteria.Nuts were assessed as either not infected, slightly infected, seriously infected or dead on randomly selected trees in each cultivar and at the four cardinal points (north, east, south, west) of the tree.The first ten nuts encountered at each point were assessed and results compared using analysis of variance.Copper/Mancozeb(R) spray was seen to have variable effects in the two years, increasing disease incidence in 2011 but reducing it in 2012.Blight infection varied significantly with cultivar and cardinal point in both years, although the results were different for the two years.In 2012 and for the number of uninfected nuts, these two variables accounted for 26.5% of the total variance compared to 8.8% for the treatments.With only one year of data, the beneficial bacteria did not appear to control walnut blight.It is suggested that wind damage is the most likely route of infection in this orchard, and that copper/Mancozeb(R) was ineffective in reducing the blight incidence particularly when disease pressure is high.This implies that in this orchard measures to reduce yield loss from walnut blight should concentrate on reducing damage (e.g., windbreaks) or increasing the inherent resistance of the tree to infection through cultural practices or cultivar selection.
walnut Juglans regia walnut blight Xanthomonas arboricola pv.juglandis environment wind damage
C.J.Bell
Corunnaire Produce 825 Nalangil Road Corunnun,Victoria Australia
国际会议
The 7th International Walnut Symposium(第七届世界核桃大会)
山西汾阳
英文
315-321
2013-07-20（万方平台首次上网日期，不代表论文的发表时间）