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Why Are My Grape Plant Leaves Turning Yellow?

Updated: May 22, 2022

If you are growing grape plants and notice that the leaves are turning yellow, it is essential to understand the underlying causes. Yellowing leaves can be an indication of several issues, including nutrient deficiencies, pests, diseases, or environmental factors. In this article, we will discuss the common reasons why grape plant leaves turn yellow and what you can do to prevent or treat the problem.

Nutrient Deficiencies

Grape plants require specific nutrients to grow and thrive. If they lack any of these nutrients, the leaves may start to turn yellow. The most common nutrient deficiencies in grape plants are:

Iron Deficiency

Iron deficiency is a common issue in grape plants, especially in alkaline soils. When the soil pH is high, the iron in the soil becomes unavailable to the plant, leading to a lack of chlorophyll production. This results in yellowing of leaves with green veins.

Nitrogen Deficiency

Nitrogen is a vital nutrient for plant growth and is responsible for producing chlorophyll. A lack of nitrogen leads to slow growth, weak stems and yellowing of leaves.

Magnesium Deficiency

Magnesium is essential for photosynthesis, and its deficiency leads to yellowing of leaves with green veins.

Pests

Grape plants attract several pests that can cause damage to the foliage. These pests include spider mites, aphids and thrips. When these pests feed on the leaves, they suck out sap from the plant, causing stress and leading to yellowing of leaves.

Diseases

Grape plants are also susceptible to diseases that can cause yellowing of leaves. The most common diseases include:

Powdery Mildew

Powdery mildew is a fungal disease that affects grape plants. It appears as a white powdery substance on the leaves and causes them to turn yellow and drop prematurely.

Downy Mildew

Downy mildew is another fungal disease that affects grape plants. It appears as yellow spots on the upper surface of the leaves and a white mold on the underside.

Viruses

Grapevine leafroll virus and grapevine fanleaf virus are two common viruses that affect grape plants. These viruses cause yellowing of leaves, stunted growth and poor fruit quality.

Environmental Factors

Environmental factors can also cause yellowing of leaves in grape plants. These factors include:

Water Stress

Overwatering or underwatering can cause stress to the plant, leading to yellowing of leaves. Grape plants require adequate watering to thrive, and you should ensure that the soil is evenly moist but not waterlogged.

Temperature Stress

High temperatures can cause heat stress to grape plants, leading to yellowing of leaves. Ensure that your grape plants are adequately sheltered from excessive heat.

How to Prevent or Treat Yellowing Leaves in Grape Plants

Preventing or treating yellowing leaves in grape plants depends on the underlying cause. The following are some measures you can take:

Nutrient Deficiencies

If nutrient deficiencies are the cause of yellowing leaves, you can apply fertiliser that contains the lacking nutrient. For iron deficiency, apply chelated iron fertiliser, and for nitrogen deficiency, apply nitrogen-rich fertilisers such as blood meal or fish emulsion.

Pests

You can control pests by regularly inspecting your grape plants and applying insecticidal soap or neem oil to affected areas. Ensure that you follow the manufacturer’s instructions when using pesticides.

Diseases

To prevent diseases, ensure that you plant disease-resistant grape varieties and maintain good hygiene practices in your garden. Remove infected plant material and apply fungicides as needed.

Environmental Factors

Ensure that your grape plants receive adequate water and protection from extreme temperatures. You can also apply mulch around the base of the plant to retain moisture and regulate soil temperature.

Frequently Asked Questions

Can yellowing leaves be a sign of overwatering?

Yes, overwatering can lead to yellowing leaves in grape plants. Ensure that the soil is evenly moist but not waterlogged.

Can I use Epsom salts for magnesium deficiency in grape plants?

Yes, Epsom salts can provide magnesium to your grape plants. Dilute one tablespoon of Epsom salt in a gallon of water and apply it to the plant’s base.

How can I control powdery mildew on grape plants?

You can control powdery mildew by removing infected plant material and applying fungicides containing potassium bicarbonate or neem oil.

In conclusion, yellowing leaves in grape plants can be caused by several factors, including nutrient deficiencies, pests, diseases and environmental factors. It is essential to identify the underlying cause to determine the appropriate treatment. Regular inspection, good hygiene practices and proper plant care can help prevent yellowing leaves in grape plants.