Late blight – Disease pressure in 2024 season highest for many years
Prolonged rainfall alternating with high temperatures provides ideal growth conditions for plant pathogenic fungi – including the late blight pathogen P. infestans. The German Farmers’ Association and the Association of the German Potato Industry have warned that the risk of massive outbreaks of late blight is higher than it has been for a long time and could jeopardise the supply of potatoes and the potato value chain.
The potato as a host plant
Along with rice, maize and wheat, the potato is now one of the world’s most important staple foods. In Germany, the area under potato cultivation was around 262,600 ha in 2023 (Federal Statistical Office, 2024).
One of the most important yield-reducing factors in cultivation is late blight caused by Phytophthora infestans. Under warm and humid conditions, this disease can cause high yield losses of 30-75% and, in extreme cases, no yield at all.
An integrated approach to crop protection, including preventive strategies such as cultural practices and variety selection, and the use of fungicides in a spraying sequence adapted to forecasting systems, is essential to control the disease. In conventional agriculture, the range of fungicidal active ingredients is already severely restricted; mancozeb, for example, will no longer be registered after 2022, and other active ingredients are expected to be phased out over the next few years. In line with the strict requirements of organic farming, the only effective direct control, in addition to preventative measures, is copper preparations. Due to their potentially harmful effects on soil, soil organisms and water, the use of these agents has been restricted to 3 kg ha-1 of pure copper within the German growers’ associations and is repeatedly the subject of controversy. The search for environmentally friendly biological products to directly control late blight has been ongoing for many years.
However, the adaptable pathogen quickly develops resistance to fungicides, new strains become more aggressive in their spread and can overcome existing resistance genes in potato varieties. As a result, some of the most effective tools for managing late blight are being lost.
Combating late blight requires a combination of methods
The high disease pressure caused by late blight in the 2024 season is a major challenge for growers. Forward-looking strategies to control Phytophthora require a combination of preventative measures such as monitoring and crop management, as well as effective fungicidal crop protection products and resistant potato varieties. Our growers are committed to using all the tools at their disposal to best protect their crops each season.
Although crop.zone technology does not replace fungicides, it can be a building block in this combined control strategy. It provides growers with a sustainable and effective solution to potato ciculation. The resulting improvements in skin formation, baking quality and shelf life, as well as easier haulm removal at harvest, contribute significantly to overall crop quality. In addition, field hygiene can be promoted through the effective destruction of potato haulm, which acts as a primary source of inoculum.