Why Are My Raspberry Leaves Turning Brown?

Raspberries are a delicious berry that many gardeners enjoy growing at home. However, you may notice the leaves on your raspberry canes turning brown, which can be concerning. Brown leaves are usually a sign that something is wrong, but don’t worry – in most cases, the problem can be easily fixed. Here are the most common causes of raspberry leaves turning brown and what you can do about it.

Sun Scald

Too much sun exposure can cause sun scald on raspberry leaves. This appears as browning or scorched areas on the leaves, especially along the edges. It happens when the leaves get too hot in intense sunlight. Sun scald is most common in young raspberry plants or when plants are suddenly moved from shade to full sun

To prevent sun scald, make sure to acclimate young raspberry plants to sun exposure gradually. And give plants afternoon shade if possible, as this is when sunlight is strongest Adding a shade cloth over the plants is an easy solution Also, make sure the plants have adequate water, as drought stress increases sun damage. Pruning off the most damaged leaves can help the plant recover.

Herbicide Damage

Certain herbicides can cause the edges or centers of raspberry leaves to turn brown. This is because some varieties are sensitive to common pre-emergent herbicides like simazine and oryzalin. The damage is usually worse if the herbicide is taken up by the roots.

When using an herbicide around raspberries, be sure to check that it is labeled for use with cane berries. And use caution when spraying near the foliage. Look for herbicide injury if the browning appears soon after application. Unfortunately, the only solution is to wait for new growth to replace the damaged leaves.

Inadequate Irrigation

Underwatering is another common culprit when raspberry leaves turn brown. Raspberries need about 1-2 inches of water per week. Drought stress causes the leaves to dry out and brown along the edges. It also leads to poor fruit production.

Make sure to deeply water raspberries about twice a week if rain is lacking. Use drip irrigation or soaker hoses to target the roots. Drooping leaves that revive after watering indicate the plant was thirsty. Damaged leaves won’t recover, but the plant will grow new ones with proper irrigation.

Nutrient Deficiencies

Lack of important nutrients can also cause browning of raspberry leaves. Potential deficiencies include nitrogen, potassium, magnesium, and iron. This often affects the older leaves first. Without enough nutrients, the plant can’t produce enough chlorophyll and leaves brown from the edges inward.

Have your soil tested to identify any nutrient shortages. Raspberries need a steady fertilizer program when actively growing and fruiting. Applying a balanced organic fertilizer before planting and monthly during spring and summer should prevent deficiency symptoms. Foliar sprays of iron, magnesium or potassium may help if a specific need is identified.

Diseases

There are several raspberry diseases that begin with leaf browning, such as verticillium wilt and raspberry leaf spot. These fungal diseases often cause leaves to turn yellow or develop brown spots before browning spreads. Spots may be concentrated along leaf veins or margins.

Prune out and destroy any canes that appear diseased. Improve airflow and avoid excessive moisture on leaves. Use fungicidal sprays as a preventative before symptoms develop. Good sanitation and using resistant varieties are also important for disease management.

Winter Injury

If raspberry leaves emerge brown in spring, the likely cause is winter damage. Extreme cold, rapid temperature changes, or drying winter winds can injure exposed canes. The leaves then appear browned, stunted, or wilted.

Protecting plants from harsh winter weather reduces damage. Leave old canes standing over winter to help insulate crowns. Wrap canes with burlap or use row cover tunnels. Providing extra mulch also buffers against temperature swings. Damaged leaves won’t recover, but new growth should fill in.

Spider Mites

Spider mites are tiny pests that feed on the undersides of raspberry leaves. Their infestations cause yellow stippling or bronzing of leaves, which eventually turn brown. Webbing may also be visible on affected leaves. Hot, dry weather encourages mites to multiply.

Blast leaves with water to dislodge the mites. Apply insecticidal soap or neem oil every 5-7 days until pests are under control. Introduce predatory mites to naturally control populations. Keep nearby weeds in check and avoid excess nitrogen fertilizer, which can spur mite outbreaks.

What To Do About Brown Leaves

When you notice browning raspberry leaves, the first step is identifying the cause. This determines how to get your plants healthy again. While discolored leaves won’t recover, the best treatment is often prevention. Give raspberries proper sunlight, irrigation, fertilization and pest management to avoid environmental stresses. Catch issues early before extensive damage occurs.

If leaf damage is minimal, the plant can regrow leaves and regain vigor. But heavily damaged canes should be pruned out. This prevents diseases and pests from spreading. Remove brown leaves from the planting area to eliminate inoculum. As a last resort, severely affected plants may need replacing to ensure good production.

Don’t let a few brown leaves stop you from enjoying the bounty of fresh raspberries! Now that you know what causes the problem, you can take action to prevent it in the future. With proper care, your raspberry patch will thrive and bear lots of sweet berries.