Raspberry leaves turning yellow: what can you do?
During the summer months, raspberry leaves should appear green and healthy. However, some growing conditions, viruses or even a lack of nutrients can cause the foliage to yellow. Read on to learn more about why raspberry leaves can turn yellow and what to do about it.
Whilst actively growing, raspberries (Rubus idaeus) can develop yellow leaves, especially between the veins, which can lead to the foliage turning brown and dying. It is often a symptom of raspberry chlorosis, but the yellowing foliage could also be caused by other climatic conditions or diseases.
Why are the leaves on my raspberry plant turning yellow?
Yellow raspberry leaves can be caused by many factors and if not treated can lead to poor yields or even the plants needing to be removed.
Possible causes of yellowing raspberry leaves can include:
- A high alkaline soil pH
- Nutrient deficiencies, such as iron, magnesium, or nitrogen
- Raspberry diseases
- Raspberry pests
- Overwatering and waterlogging
- Natural life cycle
Grow raspberries in a fertile soil that is slightly acidic with a pH of 6.5 to 6.7. To test the pH of your soil, use a home test available from most garden centres or online suppliers. Growing raspberries in an alkaline soil can lead to the plants struggling due to mineral deficiencies, making them more susceptible to stress and disease.
The most common mineral deficiencies that cause raspberry chlorosis and the leaves to turn yellow are iron and magnesium, but low nitrogen can produce symptoms as well. A first sign of iron deficiency is the youngest leaves turning yellow in between their green veins, whereas a lack of magnesium often affects the older foliage first. Nitrogen is necessary for the raspberry’s vigorous cane production, and if levels are low, symptoms can include the lower foliage turning yellow, including their veins when severe, and weak growth.
Some raspberry diseases and pests also lead to yellowing raspberry leaves. If Raspberry leaf and bud mite (Phyllocoptes gracilis) is present, it can lead to the foliage developing small random yellow blotches and the growing tips appearing twisted. Raspberry vein chlorosis virus can cause some yellowing of the veins, as opposed to chlorosis, which is more visibly widespread.
Too much moisture can also cause yellow raspberry leaves. Excessive over-watering or prolonged wet weather can lead to the roots sitting in water, reducing root and leaf transpiration. This, in turn, means the plants are unable to absorb any iron and other nutrients from the soil and transport them to the foliage. When grown in containers, extreme over-watering can also flush the soil’s nutrients and minerals out of the pot, depleting the soil.
Tip: raspberry chlorosis should not be confused with the foliage naturally yellowing and dying back in late autumn, which is nothing to worry about and is simply part of its annual life cycle.
Preventing and treating yellow leaves on raspberry plants
If you discover that your raspberry leaves are turning yellow some measures can be taken to treat it. By fertilising raspberries properly and following best practice advice for growing raspberries, most causes of raspberry chlorosis can be avoided in the first place.
If the soil’s pH is too alkaline for growing raspberries, the pH can be lowered by adding sulphur according to the manufacturer’s instructions. Ericaceous soil, such as our Plantura Organic Ericaceous Compost, or pine needles can also be thoroughly dug into the whole planting area to make it more acidic. However, the process of soil organisms converting the sulphur or organic matter to make the soil more acidic can take months. Any necessary lowering of the soil’s pH should be done well ahead of planting and as an ongoing measure to help keep the pH low.
- Perfect for acid-loving plants such as hydrangeas, rhododendrons, blueberry bushes, azaleas & more
- Ensures all-round healthy plants with lush blooms and aromatic berries
- Peat-reduced & organic soil: CO2-saving composition
Perhaps the most common cause of yellow leaves on raspberry plants is chlorosis caused by nutrient deficiencies. Planting raspberries in a fertile soil enriched with well-rotted manure and a general fertiliser will go a long way in helping prevent chlorosis. However, as they are hungry plants, you should fertilise raspberries during the growing season as well. Feed raspberry plants from spring until summer with a nitrogen-rich fertiliser, such as our Plantura Liquid Tomato Food, to prevent or treat nitrogen deficiencies.
- Perfect for tomatoes & other vegetables
- Liquid fertiliser for healthy plant growth & an abundant harvest
- Quick & easy application - child & pet friendly
If chlorosis is identified on otherwise healthy raspberries and the soil’s pH is a suitable 6.5 to 6.7, a lack of iron or magnesium is likely the cause. To treat a lack of magnesium or iron, an application of a foliar fertiliser, containing chelated iron or manganese sulphate, can help rectify the problem.
Raspberry diseases can also cause yellow raspberry leaves. The Raspberry vein chlorosis virus is spread by an aphid (Aphis idaei) and with no controls available other than growing resistant cultivars, any affected plants should, unfortunately, be dug up and destroyed. The Raspberry leaf and bud mite is a raspberry pest that affects raspberry yields and can cause pale yellow areas on the foliage. If yields are unaffected this pest can be tolerated, but if harvests are poor, it is best to replace any plants with less susceptible cultivars.
Tip: feed your raspberry plants with a nutrient-rich fertiliser to make them healthier and more robust, which will help prevent them from succumbing to pests or diseases.
Raspberries are best grown in moist but well-drained soil. However, excessive overwatering or continued wet weather can lead to yellowing leaves as well. Once established, raspberry plants should be watered in dry conditions, but any overly wet or soggy soil should be avoided as this can lead to their foliage yellowing. To prevent any issues arising from wet soils, plant raspberries in a sunny spot on free-draining soil that is not prone to becoming waterlogged.
When growing raspberries in pots, ensure adequate drainage holes to allow any excess water to drain away. To aid drainage further, add a layer of gravel or broken crocks to the bottom of the pot before adding the soil.
Along with the preventative measures discussed, if you fertilise raspberries correctly and prune raspberries according to their variety, then yellowing foliage can usually be prevented.