Impact of LED and weak EM fields on grapevine
Impact of LED light and weak modulated low frequency EM-RF emission on grape (grapevine) has been specifically investigated ,,,. Different aspects of the development of roots and apices are studied . For instance, it is shown that red- and blue-light-emitting diodes have effect on shoot and root growth of Hybrid Franc grape, a rootstock cultivar, along with two other grape genotypes . Plants cultured under red-light-emitting diodes produced the longest shoots with longer internodes for all genotypes. The chlorophyll content measured as SPAD value and leaf number per explant were highest on plants cultured under blue-light-emitting diodes in all the genotypes. Blue light was also responsible for a higher number of stomata in all the genotypes. The red-light emitting diodes gave a higher rooting percentage along with higher root numbers for the two other grape genotypes . Not only the LED light but also modulated low-frequency electromagnetic fields were applied to canes of different grapes. For example, the parameters of vigour (shoot growth) of the first three weeks, bud-break percentage of the first three weeks, bud-break percentage, vigour, rooting percentage, root development, root weight, number of root, shoot length, shoot weight, number of node, node height, root/shoot weight and shoot + root weight were included in the study . As a result, different durations of 50 Hz frequency resulted in significant differences on mean rooting percentage, mean root development, mean root weight, mean number of root, mean shoot weight and mean shoot+root weight . Especial attention is paid to the development of an effective control strategy for grapevine deceases, such as esca. Experimental trials were carried out in vineyards and single infected vines in order to evaluate the effectiveness of different fungicides, application methods and cultural practices in controlling esca  or other fungal diseases.
- Peronospora (Plasmopara viticola) is a fungal disease that can cause wine to considerable damage. After the pathogen in 1878 was introduced from North America to southern France and spread within a few years all over Europe. The fungus attacks all green parts of vines. The first symptoms develop on the leaves yellowish stains (oil spots) and on the underside of leaves, a white fungal growth (consisting of spore carriers). After the death of the leaf, the affected leaves turn brown and fall off (leaf fall disease). The infected flower clusters tend downwards, which are later also covered by white fungal growth. After flowering, the berries of the affected grapes shrivel, turn blue-black (leather berries), and the steems of the grape die. An infection of flower during flowering caused the highest yield losses.
- Esca is a fungal disease, which is caused by various pathogens. The disease has long been known and occurred mainly in Mediterranean countries. Meanwhile, it can be found throughout Europe and provides for the wine represents a significant threat. This phenomenon is in recent years increasingly to observe and means for wineries partly a serious economic damage. Just old vines that produce the better qualities, must be cleared and replaced with young vines. It then takes three years until the young vine again bears grapes, but not in the usual quality.
- Oidium (Oidium tuckeri) or powdery mildew is a fungal disease that can lead to considerable damage. The fungus comes from North America and was introduced to Europe in 1845. The fungus can infect all green parts of vine. The first infestation already appears in the spring on the young shoots, which remain in the growth and are covered with a white-grey fungal growth. On the bottom of the sheet is a white fungus lawn and on the leaf top side a yellowish whitening. The fungus lawn can take over the entire sheet. In this case the leaves curl and become brittle. The flower cluster are covered with a white grey fungus lawn during early infestation and die later. The green berries are still affected, superficial grows a white-gray fungus grass, destroying the grape skin, the berry grows further, the berries burst and the seeds are visible. The attack on the green shoots is noticeable by gray patches, which turn brown violet at starting lignification.
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