All living organisms have their own method for getting through the winter period of dormancy. Some accumulate layers of fat under their skin, some retreat underground or to other sheltered locations, and others cope with this inhospitable period in a state developed specifically for the purpose. Naturally it is not only plants and animals that prepare for winter: humans do so too. We collect firewood or fill our strategic gas reserves. And farmers perform maintenance work on their machinery, for example making sure that the pumps, filter housings, and spray nozzles of spraying equipment are in order. What tasks are there in plant protection?
The conditions of our warming climate allows pathogens to proliferate. If no plant protection measures are taken after harvesting, whole months can pass when fungi, hitherto strictly and expensively kept in check, can roam free without any limitations. These end up wintering in large numbers, with some even breeding (e.g. Taphrina deformans, responsible for peach leaf curl, breeds above 4°C) or infecting (e.g. Pseudomonas syringae pv. syringae, responsible for bacterial canker in apricot) during the winter months. In any case, they await spring with large amounts of propagules and cause a substantial infestation rate.
The experience gained over the course of centuries shows that dormant application is one of the most important basic plant protection procedures in spraying. However, recent years have seen this technology being reduced to dormant application only at the end of winter. The spring (end-of-winter) delayed-dormant application is a useful technology, of course only if it is applicable. As our climate becomes increasingly extreme, the quick spring thaw often results in the optimal time for dormant application to be missed. As a result, pathogens encounter no limitations in the crop.
The time has therefore come to rethink the timing of dormant application, with especial regard to autumn treatments. The lengthy autumn period is perfectly suited to decimate the pathogens seeking shelter on shoot surfaces, around wounds, and in the cracks of barks. Several pathogens could be listed for almost all fruit cultures (pome fruits, stone fruits, nuts, berries, grape) that can be successfully treated with autumn dormant application. The application of the autumn treatment is recommended together with copious amounts of spray, starting with the falling of leaves.
A number of factors have to be taken into account when reviewing the limited range of available dormant products. One the one hand, it is useful to select a product that contains more than one active substance, as that allows simultaneous protection against a variety of different pathogens. Furthermore, environmental protection factors also have to be considered. The metallic copper content in dormant application products is added to the amount of copper sprayed during the vegetation period, the total of which cannot exceed 6 kg/ha. In fact, this amount is expected to be decreased by future EU regulations.
In light of experience in application, the freely-trafficked product Vegesol eReS, which contains copper and sulphur active substances in an oily mixture, meets all of the above conditions and is a popular solution for dormant application. This brand name now encompasses all of the biological effects expected from autumn and spring delayed dormant application, resulting in the ideal product, Vegesol eReS.