Abstract
Coffee Berry Disease(CBD) caused by Colletotrichum kahawae is a destructive fungal disease of coffee in Kenya, leading to a loss of about 75%. This study aimed to assess the In Vitro efficacy of two fungicides:- CRI 1 (Pyraclostrobin 150 g/L + Fluxapyroxad 75 g/L) and CRI 2 (Pyraclostrobin 128 g/Kg + Boscalid 252 g/Kg) against C. kahawae using poisoned food technique on Potato Dextrose Agar. A total of 170 coffee berries with C. kahawae symptoms were purposively collected from both sprayed and unsprayed plots. Ten rates of each of the two fungicides were assessed ranging from 0.01% to 0.1% at an interval of 0.01%. Two commercial standard fungicides Pyraclostrobin 250 g/L at 0.04% and Tebuconazole 200 g/L + Trifloxystrobin 100 g/L at 0.1% were used as positive controls. Fungal inoculum in PDA media devoid of the fungicide acted as the negative control. Data on colony diameter was collected after every 24 hours for 13 days. Analysis of Variance (ANOVA) of the data on colony diameter was done using CoStat software version 6.400. The results revealed that all the rates of CRI 1 and CRI 2 fungicides controlled the colony diameter of C. kahawae compared to the control treatment. CRI 1 fungicide suppressed the growth of C. kahawae even at the lowest concentration of 0.01% with a percentage control of 64.74 %. The highest concentration of 0.1% had a percentage control of 66.15% . CRI 1 is more effective in controlling C. kahawae since it controls the fungus at a rate even lower than Pyraclostrobin 250 g/L which had a percentage control of 66.10 at a recommended rate of 0.04% and Tebuconazole 200 g/L + Trifloxystrobin 100 g/L fungicides which had a percentage control of 65.76 at a recommended rate of 0.1%. CRI 1 also hade a better percentage control as compared to CRI 2. CRI 2 had a percentage control of 54.63% at the highest rate of 0.1% and a percentage control of 35.60% at the lowest rate of 0.01% . Further studies on CRI 1 and CRI 2 fungicides should be carried out for yield assessment in the field.
Highlights
Coffee is the most important raw material traded throughout the world after crude oil.[1]
Isolate 1 of C. kahawae fungal pathogen was obtained from Rukera farm at CRI where fungicides are applied for control of Coffee Berry Disease (CBD) while isolate 2 of C. kahawae was obtained from Coffee Research Institute coffee farm, where fungicides are not applied
CRI 1 Fungicide percentage control increased with the increasing concentration from 0.01% to 0.1% (Table 2)
Summary
Coffee is the most important raw material traded throughout the world after crude oil.[1] Coffee sustains over 100 million people globally and is rated among the largest export commodities in the world.[2] Coffee is the fifth largest foreign exchange earner in Kenya after tourism, tea, horticulture and diaspora remittances[3] and has largely contributed to the Kenyan economy through foreign exchange earnings, as well as creating employment opportunities.[4]. Coffee production in Kenya faces a major challenge from Coffee Berry Disease (CBD). The disease is caused by Colletotrichum kahawae, an anthracnose of green and ripe berries. The coffee fruit is colonized by infection hyphae that arise from the appressoria. The symptoms start to appear that includes; dark, necrotic sunken spots and brown, superficial lesions.[7] The disease causes premature fruit fall and mummified or damaged fruits which leads to a loss of about 75% of coffee.[8]
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