News and knowhow for farmers

Potato Center introduces simple paper card cutting fungicide use by 50%

The International Potato Center (CIP) has introduced a simple decision support tool (DST) made from card paper and available via the Android app store that makes tracking and managing spray records for potato late blight easier.

In field trials done in Kenya, DST halved the number of sprays from 12 to six while maintaining and in some cases increasing harvest yields. A reduction in the number of sprayings translated to reduced fungicide, labour, and time costs.

The tool which tracks rainfall events and the last spray date, can be used remotely and does not require potato farmers to be tethered to their farm tracking what is going on at all times.

Since 2008, Kenya’s potato production has shrunk by 62.5 per cent to just 8.4 t/ha in 2022. This is well below the country’s 30 to 40 t/ha production potential. The main culprit for this has been potato late blight.

Because late blight thrives in cooler conditions, during the wet season, fungicide application can go up to three times a week. In Kenya’s main potato-producing region of Nyandarua County, 43 per cent of potato farmers apply fungicides once a week, 21 per cent twice a week, and 3.8 per cent thrice a week.

DST helps farmers tackle when to best apply fungicides, which fungicides to apply at any one time, and how frequently they should be used.

“Using the DST is simple: pick the color disc for your potato variety—red for susceptible, yellow for moderately tolerant, and green for highly tolerant. Then, check if there’s been any rain since your last spray, and note the frequency and the days since your last fungicide application. The DST gives you a customized recommendation by adding up the corresponding numbers on the disc,” read part of the CIP press release.

The tool also encourages farmers to alternate chemicals which helps avoid the build-up of potato late blight resistance. “Almost all potato farmers in Kenya rely solely on synthetic pesticides to control late blight. Of these farmers, 66 per cent use only one pesticide type (mancozeb) to control the disease. This has encouraged the disease’s resistance making an already bad situation even worse,” — Kenya’s potato late blight resistance ticking time bomb for Sh50B agri-sector.

Alternating between different types of fungicides such as Cymoxanil, Mancozeb, and Metalaxyl achieves healthier crops with higher yields compared to conventional methods that rely solely on one fungicide. 

According to the CIP report, during periods of low disease risk conditions, i.e., low rainfall and low to moderate humidity, the DST often recommends farmers either not to spray or to apply contact fungicides which are cheaper and more environmentally friendly. 

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