PROGRESS REPORT

2017

Cercospora leaf-spot (CLS), caused by Cercospora beticola, is an important foliar disease of Swiss chard in Botswana. The regularity of outbreaks of the disease in Botswana is a major cause of concern and thus, have necessitated the use of fungicides under field conditions in order to control the disease and bring the crop to maturity. The objective of the study was to assess the most effective, locally available fungicides in the control of CLS of Swiss chard under field conditions. The experiment was carried out in Sebele, where a tractor-ploughed field was partitioned into 24 plots, which were split into three blocks. Seedlings were transplanted into the plots, with each plot containing a maximum of 45 plants which were left for natural infection. Disease control commenced once symptoms were observed, using Copper oxychloride; Benomyl + Mancozeb; Mancozeb + Copper oxychloride; Benomyl; Benomyl + Copper oxychloride; Mancozeb; Benomyl + Mancozeb + Copper oxychloride applied at reco...

Plant Disease, 1997

2018

= low risk; ** = moderate risk; *** = high risk 1 polythene covered crop; 2 waste piles; 3 volunteers; 4 oospores possibly involved; 5 allotment garden Ninth Workshop of an European Network for development of an Integrated Control Strategy of potato late blight Tallinn (Estonia), 19-

Most economical schedule was T3 i.e., spray with Fenamidone @ 0.2% at disease initiation stage and 2nd spray of Mancozeb @ 0.25% followed by Mancozeb @ 0.25% at 15 days intervals was found most effective in controlling the severity of early blight and increasing tuber yield in comparison to other treatments and proved to be most economical with higher benefit cost ratio of 1:6.59 and1: 6.85 in year 2012-2013 and 2013-14, respectively. The highest benefit cost ratio was recorded in the plots treated with Fenamidone @ 0.2% at disease initiation followed by two more spray of Mancozeb @0.25% at 15 days intervals. It was found superior with same fungicidal schedules in both years. All other treatments with alteration were also found beneficial in respective order of both years.

Journal of Cereal Research, 2020

Eleven fungicides were evaluated as two foliar sprays for the management of yellow rust (Puccinia striiformis) at CSKHPKV, RWRC, Malan. Seven fungicides were tested during both the cropping seasons whereas, two each were evaluated during 2015-16 and 2016-17. Tebuconazole 25 EC @ 0.1% was the most effective with mean disease severity (MDS) of 1.84 % and mean disease control (MDC) of 99.64% over the unsprayed check (48.39%) followed by Nativo 75WG@0.05%, Amistar 250 SC, Propiconazole and Amistar Top 325 SC @ 0.1%. The highest mean grain yield of 32.24 q/ha was recorded in two sprays of Azoxystrobin 20%+Difenconazole 12.5% SC @0.1% with mean increase in yield of 56.73% over check with corresponding net profit of Rs. 14815 and cost: benefit ratio of 1: 2.93. It was followed by 32.10, 31.47, 31.18 and 29.65 q/ha yield in Tebuconazole 25% EC, Azoxystrobin 23.1%SC, Tebuconazole 50%+ Trifloxystrobin 25% w/w 75WG and Propiconazole 25%EC, with mean yield increase of 11.54, 10.91, 10.62 and 9.08 q/ha with 56.08, 53.01, 51.60 and 44.14 % over the unsprayed check with net profit of Rs. 16705, 13187, 13384 and 13479 and with corresponding cost: benefit ratio of 1: 4.03, 1:2.68, 1:2.89 and 1:4.36, respectively. On the basis of one year data, the highest grain yield of 37.08 and 32.24 q/ha was recorded in Score 250 EC and Opera @0.1% with 64.80 and 72.96% increase in yield over check with cost: benefit ratio of 1: 3.53 and 5.38 respectively. Duncan’s Multiple Range Test (DMRT) implied that effect of years on disease severity was non-significant, all the test fungicides resulted in significant reduction in disease severity and treatments Tebuconazole 25% EC, Tebuconazole 50%+ Trifloxystrobin 25% w/w 75WG, Azoxystrobin 20%+Difenconazole 12.5% SC and Azoxystrobin 23.1%SC showed significantly more yield than the other fungicides. These fungicides may be used against this disease as a short-term alternative of resistant varieties.

Crop Protection, 1995

A series of 23 field experiments was undertaken from 1984 to 1986 to investigate the optimum timing of foliar application of prochloraz for control of eyespot on winter wheat. The possibility of delaying the prochloraz application from GS31 to GS32-33 or GS37-39 as a means of reducing the overall number of fungicides required to optimize profitability was investigated in a further series of 24 experiments from 1987 to 1989. Applications of prochloraz between GS30 and GS32-33 were equally effective for eyespot control at most sites, although in one year treatment was less effective at GS32-33 than at GS31. Later applications, at GS37-39, were less consistent, although in some years they were as effective as applications between GS30 and GS33. Early February was the optimum time of prochloraz application on one very advanced crop which reached GS30 by the end of January. In the 1987-1989 experiments, prochloraz alone at GS37-39 was less effective than the best treatments for control of yellow rust and Septoria tritici. Treatments with three fungicide applications for control of these foliar diseases gave the highest yields at many sites but, except where their incidence was particularly high, treatments with one or two fungicide applications were often more cost-effective. Yield increases following fungicide treatment were associated with increases in thousand-grain weight and, at some sites, in specific weight. It was concluded that where there was a high risk of either eyespot or foliar disease specific fungicide applications were required for each, but where the disease risk was lower it was sometimes possible to control both with a single application.

2014

Vegetable crops are frequently infected by fungal pathogens, which can include seedborne fungi. In such cases, the pathogen is already present within or on the seed surface, and can thus cause seed rot and seedling damping-off. Treatment of vegetable seeds has been shown to prevent plant disease epidemics caused by seedborne fungal pathogens. Furthermore, seed treatments can be useful in reducing the amounts of pesticides required to manage a disease, because effective seed treatments can eliminate the need for foliar application of fungicides later in the season. Although the application of fungicides is almost always effective, their non-target environmental impact and the development of pathogen resistance have led to the search for alternative methods, especially in the past few years. Physical treatments that have already been used in the past and treatments with biopesticides, such as plant extracts, natural compounds and biocontrol agents, have proved to be effective in controlling seedborne pathogens. These have been applied alone or in combination, and they are widely used owing to their broad spectrum in terms of disease control and production yield. In this review, the effectiveness of different seed treatments against the main seedborne pathogens of some important vegetable crops is critically discussed.