CULTIVATION AND TECHNOLOGY Secrets revealed about Early blight and Pseudo-early blight 4D-PROJECT 4D-project stands for Digital Detection and Diagnosis Service, which aims at recognising diseases in crops at a distance, on which basis advice is given to crop growers so that they are able to manage their crops and possible diseases in the best possible way. For their pilot project, they took the potato as a crop and the Early blight fungus as the pathogen. This project is funded by the province of Drenthe (Drenthe Innovative Action Programme) and the European Regional Development Fund. Astron, AVEBE, Bayer and Ordina are also involved in this project together with HLB. Symptoms of boron deficiency in foliage of the Mimi variety. Note the thickened and stiff leaves, the concrescence of the top leaves, the deformation of the margins of the leaves, and the shortened petiole and petioles. Boron deficiency also causes lesions. However, the Mimi plants showed some other rather striking symptoms such as thick and stiff foliage, damaged leaf margins, concrescence of the top leaves on one or both of the top leaves and shorter leafstalks and stems. These are all symptoms of severe boron deficiency. Besides being important for healthy development and longitudinal growth, boron is also needed for a proper assimilation process. In other words, the formation of sugar from carbon dioxide and water under the influence of sunlight. During this process, energy is absorbed from sunlight and broken down into smaller parts and released to the energy carriers of the plant cells. This is a rather critical process in which things can easily go wrong, resulting in the release of radicals. Radicals are highly oxidizing particles that impair other molecules whereby a great amount of damage is caused. Boron is involved in preventing these radicals from causing damage. Ozone is also a radical and it is natural to assume that boron is also involved in preventing damage by super oxidation by ozone. In 2009, many early-maturing potato plants were found. What this, in fact, means is that there is a Table 1. Summary of the results in determinating the presence of Alternaria solani in Alternaria-like lesions of samples sent in during the 2009 growing season. Information Samples sent in Samples with A. solani Samples without A. solani Prepared lesions in which Alternaria solani Until 21 July to 4 to 18 21 July to 21 July 3 Sept. 22 0 22 286 0 59 19 40 301 68 Sept. 31 29 2 181 151 18 Sept. 112 48 64 768 219 Typical of old Early blight lesions is that they can be accompanied by small, new lesions resulting from spores that have dropped off the bigger lesion. complex problem caused by boron deficiency and, on top of that, ozone damage. Yet, the problem can be better controlled than is generally thought. Although the ozone problem in itself is not so easily solved, boron deficiency can simply be prevented by applying boron when the soil is being prepared depending on the condition of the soil, up to one kilogram per hectare. Findings regarding of the Alternaria alternata situation In everyday life A. alternata is often mentioned in the same breath as A. solani as the cause of foliage lesions in potatoes. It is questionable, however, whether this is true. Within the framework of a study into the causes of Alternaria-like lesions, carried out during the period from 25 June to 18 September 2009, samples of leaves with supposed Early blight symptoms were collected throughout the country and examined. From 25 June, samples were sent in, immediately examined for type of lesion and photographed. Almost all analysed samples were characterised by the presence of lesions with concentric rings. Each sample was put under the microscope and checked for A. 22 Potato World 2010 • number 4 Pagina 21
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