Brown spots on the leaves of the grapevinemay indicate the presence of a fungal disease, pest attack or improper fertilization. Seewhere the brown spots on grapevine leaves come fromand how to identify the symptoms that indicate the cause of the spots. We suggest how to get rid of brown stains from grapevine leaves, what to usespray against stains on grapevine leavesand how to choose the right fertilizers, thanks to which the grapevine will have beautiful, he althy leaves.
Brown spots on the leaves of the grapevines indicating a deficiency of potassium or magnesium
Fig. pixabay.com
Brown spots on grapevine leaves due to fertilization errors
Brown spots on the leaves of grapevines are one of the symptoms that appear on shrubs in the case of a deficiency of some macro- and microelements in the soil. In order to supplement them, we must reach for appropriate fertilizers.
Brown spots on the leaves of grapevines may be a symptom of potassium deficiencyPotassium deficiency most often appears in vines growing on light and sandy soils (potassium is easily washed away from such soils).The edges of the leaves and some of the spaces between the veins turn yellow and dry, and brown spots may appear on the leaves. Symptoms of potassium deficiency appear at the earliest on older leaves near the clusters. Potassium deficiencies in the soil can be supplemented by using potassium sulphate for fertilization.
Brown spots on grapevine leaves may be a symptom of calcium deficiency These symptoms appear at the earliest on young leaves -the edges of the leaves curl, and brown necrotic spots appear on the bladesThe effect of calcium deficiency are also rare clusters and little sweet fruit. If you want to make up for the deficiency of this ingredient, use calcium nitrate.
In turnas a result of magnesium deficiency, the leaves of the grapevine turn yellow or redden between the veins , which remain green. The 'Aurora' grape variety develops the characteristic yellow, and over timebrown spots at the edges of the leaves and between the veinsMagnesium deficiencies in the soil can be supplemented with magnesium sulphate.To effectively prevent the occurrence mineral deficiencies in the soil, it is worth using mineral fertilizers to fertilize grapevines with a full set of ingredients needed by this plant, such as Target fertilizer for vines with microelements.
Brown spots on grapevine leaves caused by disease
Brown spots on the leaves of the grapevine may be a symptom of a fungal disease . The most common symptoms are powdery mildew, both downy mildew and powdery mildew, but there are equations between the two diseases.
Mianowice downy mildew of grapevines develops on leaves and immature clusters. The characteristicsymptom of downy mildew is olive-yellow spots that turn brown , and a white-gray coating appears on the lower side of the leaf blade. The stains gradually dry up. On older leaves that have finished growing, the spots appear mosaic. Affected berries take on a greyish-brown color and, as a rule, form dried up mummies. Downy mildew grows rapidly in warm and humid weather.
Symptoms of downy mildew on grapevines
The natural plant protection agent Limocide will help against downy mildew. Spraying with this preparation can be performed preventively or when the first symptoms of the disease appear, from the second leaf stage to the end of the inflorescence stage, at intervals of 10 - 14 days. The preparation is dosed in the amount of 2 ml per 1 liter of water.A maximum of 6 sprayings per season can be done.
On the other hand,powdery mildew can be recognized by yellow-green spots covered with a whitish white coatingon the upper side of the leaf. Often, spots appear on young vine leaves. When the disease is severely severe, young leaves turn upwards, undergoes severe deformation, and the bloom may also be visible from the lower side of the leaves. Powdery mildew is particularly intense during sunny and warm summer, and it can also attack inflorescences and young berries.
As a preventive measure against the powdery mildew of grapevine, it is worth using the ecological Lecitec preparation, based on natural lecithin. Lecithin blocks the fungus from penetrating the plant tissues. We dose it in the amount of 25 ml per 8 liters of water. Spraying with Lecitec is performed several times during the growing season, repeating every 5-7 days.
In the case of severe powdery mildew infestation, you need to use the plant protection agent Siarkol 800 SC.This spraying should be used as a preventive measure or at the first symptoms of the disease, every 7-10 days, dissolving 27.5 - 40 ml of the agent in 10 liters of water. A maximum of 8 sprayings per season can be performed.
Pest-induced brown spots on grapevine leaves
The reason for the appearance of brown spots on the leaves of the grapevinemay be the spider mite and the fruit spider mite feeding on the plant. Both pests have similar symptoms. The moving stages suck the sap from the lower side of the leaf, covering it with a delicate spider web. The puncture site is surrounded by a small colorless spot that turns brown over time. As a result,small brown spots on the leaves of the grapevine are formedThe leaves begin to deform when the pest is very numerous. Dry and sunny weather favors the occurrence of spider mites, which may spend several generations during the growing season.To combat spider mites, you can use such agents as: Polysect 005 SL or Karate Zeon 050 CS, but in amateur cultivation on the plot, we recommend using mainly natural Emulpar 940 EC, based on natural rice oil.We use Emulpar in the amount of 90-120 ml of the preparation per 10 liters of water. It can be sprayed in the early spring, in order to control wintering spider mites, as well as in the vegetative season, after the symptoms of pests are noticed.
MSc Eng. Joanna Białowąs
