Why Are My Strawberry Plant Leaves Turning Brown?

Discovering brown leaves on a strawberry plant is a common issue for many gardeners. This discoloration signals that the plant’s environment or care routine needs adjustment. This guide will help you diagnose the reason for the browning and provide clear steps for treatment and prevention.

Environmental and Care-Related Causes

Watering practices are a primary factor in browning leaves. Overwatering leads to waterlogged soil that suffocates roots, causing them to rot. Damaged roots cannot absorb nutrients effectively, resulting in soft, brown leaves.

Conversely, underwatering causes leaf edges to become crispy and brown. You can check soil moisture by inserting a finger a few inches deep; if it feels dry, it’s time to water. The goal is to maintain consistently moist, but not saturated, soil.

Excessive, harsh sunlight can lead to sun scorch, which appears as large, dry, brown patches on the leaves where the tissue has burned. While strawberries need sun, those in hot climates may require partial shade during the hottest part of the day to prevent this damage.

Nutrient deficiencies can also cause browning. A potassium deficiency causes leaf margins to turn brown, a condition known as necrosis. A calcium deficiency may cause the tips of new leaves to brown, while a lack of magnesium can contribute to browning around the leaf edges.

Fungal Diseases Causing Brown Leaves

Fungal diseases, which thrive in warm and moist conditions, are a significant cause of brown leaves. These diseases can weaken the plant, reduce fruit production, and in severe cases, can lead to plant death.

Leaf spot (Mycosphaerella fragariae) first appears as small, round purple spots on the leaves. As the infection progresses, these spots enlarge and develop tan or grayish-white centers with a reddish-purple border. The lesions can also appear on fruit stems and caps.

Leaf scorch (Diplocarpon earlianum) begins as numerous small, irregular purple or brownish spots on the upper leaf surface. Unlike leaf spot, these spots do not develop a light-colored center. As the disease advances, the tissue between spots can turn reddish, and the leaf margins will dry and curl, giving it a scorched appearance.

Leaf blight (Phomopsis obscurans) produces larger lesions, starting as one to six reddish-purple circular spots on a leaflet. These lesions expand, often forming a V-shape along the leaf’s veins, with a light brown center and a darker border.

Pest Infestations Leading to Damage

Pest infestations can lead to browning leaves as insects feed on the plant’s tissues and sap. This damage stresses the plant, making it more susceptible to other issues.

Spider mites are tiny arachnids that are difficult to see, but their damage is noticeable. They suck sap from the undersides of leaves, creating tiny yellow or brown dots called stippling. In heavy infestations, the entire leaf can turn bronze or brown, and you may see fine webbing.

Aphids are another sap-sucking insect that can affect strawberry plants. While their feeding causes leaves to yellow and curl, a severe infestation can stress the plant to the point that leaves begin to brown and die back. Aphids also excrete a sticky substance called honeydew, which can lead to the growth of sooty mold.

Treating and Reviving Your Strawberry Plant

The first step for any issue is to prune away all affected foliage. This improves air circulation and prevents the spread of fungal spores or pests. Destroy the removed material rather than composting it to avoid reintroducing the problem.

For environmental issues, adjust your care routine. If overwatering was the problem, let the soil dry more between waterings and ensure good drainage. For underwatering, create a consistent watering schedule. If a nutrient deficiency is suspected, applying a balanced fertilizer or a specific supplement, like a potassium-rich feed, can help.

For fungal diseases, apply products containing copper or other approved fungicides. For pest problems like spider mites and aphids, use insecticidal soaps. Always follow product instructions carefully when applying any treatment.

With the source of stress removed and proper care provided, the plant can focus on growing new, healthy foliage and has a good chance of recovery.

Preventing Brown Leaves in the Future

The best long-term strategy is prevention. Water the base of the plant in the morning, allowing the foliage to dry during the day. This reduces the risk of fungal infections that thrive on wet leaves.

Good air circulation is also important for disease prevention. Space strawberry plants 12 to 18 inches apart so air can move freely between them. This lowers humidity around the leaves, making conditions less favorable for fungal growth. Regularly removing weeds also improves air circulation.

Applying a layer of mulch, such as straw, around the base of the plants is also beneficial. Mulch helps retain soil moisture, suppresses weeds, and creates a barrier that prevents soil-borne pathogens from splashing onto the leaves. It also keeps developing fruit clean.

Make regular inspection part of your routine. By checking plants frequently for early signs of trouble, like small spots, you can intervene quickly. Early detection makes it easier to manage issues before they become severe. Choosing disease-resistant varieties when you first plant also provides a significant advantage.