Raspberries are popular in home gardens. Raspberries are easy to grow and produce a heavy yield if you take good care of them. Since raspberries are self-fertile, you can even grow a single bush to produce fruit. Raspberry plants are unlike many other fruits. Raspberries won’t take long to grow and will give you sweet juicy fruit within two years of planting.
Raspberries are hardy plants. Like any other fruit crop, raspberries aren’t without their problems. Raspberry growers can sometimes run into issues, such as diseases or pests that can hinder growth and limit yield. Continue reading to learn all about raspberry plant problems.
Find out how to manage raspberry plants so you can enjoy them throughout the summer.
Raspberry Plant Problems And Management
Raspberry plant problems fall into many categories. Let’s discuss each category and see what issues fall into each of these. We will also go through some practical tips on how to manage them.
The worst problems that a raspberry bush can encounter are viral infections. These are the worst because there is no cure for viruses.
Viruses spread from the infected raspberry bushes by pests, such as aphids, nematodes, and leafhoppers.
Once a virus hits a raspberry plant, it will develop on the bush and render them completely unproductive in a span of 2 to 3 years.
If your raspberry bushes have a viral infection the only thing you can do is pull up the bush and roots and destroy it. This will help stop the disease from spreading to other raspberry bushes.
Some gardeners wait until the plant is no longer productive before removing the infected bush. If you plan on replacing the uprooted plant with a fresh stock, never plant it in the same location.
Once infected by a viral disease, a raspberry bush cannot be saved. Prevention is the only way you can prevent the problem from occurring in the first place. Buy stocks that are resistant to viruses and protect them from pests to further reduce the chances of infection. Viruses are often transferred from surrounding host plants, including weeds. Control weeds around the raspberry bush by mulching and removing any weeds that appear in the area. Once the garden is cleared of potential host plants, there will be fewer chances of encountering viruses.
Types Of Viruses
There are multiple viruses that are a threat to raspberry plants, each one with its own symptoms. Here are some that you need to look out for:
Caused by: Raspberry Leaf Curl Virus (RLCV)
Transmitted by: Aphids
Symptoms: Rounded leaves curving downwards, new shoots are yellowish and smaller than usual.
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Raspberry Bushy Dwarf
Caused by: Raspberry Bushy Dwarf Virus (RBDV)
Transmitted by: pollen
Symptoms: yellowing leaves, smaller cane height, reduction in yield, and plant strength.
Raspberry Mosaic Disease
Caused by: Black raspberry necrosis virus (BRNV), Rubus yellow net virus (RYNV), and Raspberry leaf mottle virus (RLMV)
Transmitted by: Aphids
Symptoms: weak canes, leaves curve upwards or downwards, green spots on leaves.
Caused by: Nepovirus TRSV
Transmitted by: certain species of nematodes
Symptoms: yellow veins or rings on leaves, yellowing on canes and poor development of fruit.
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Raspberries are susceptible to fungal diseases. There are different kinds of fungi that can affect raspberry plants. Different fungal diseases have different symptoms. Some are easier to manage than others. Depending on which fungal disease you are dealing with, you might need to destroy the infected plant instead of fixing it.
Here are some of the common fungal diseases that affect raspberries:
Raspberry cane blight is a fungal disease caused by the fungus Leptosphaeria coniothyrium. The fungus is spread through splashing water from irrigation or rainfall. It enters the canes through small wounds, weakening them from inside and eventually causing the canes to die back.
Large, brown, dead areas appear on canes. The cankers enlarge, causing wilting of the lateral shoots.
The fruiting canes should be removed and destroyed right away once you’ve harvested the raspberries. Cut back the infected canes below the canker and destroy the pruned debris.
Always select resistant varieties and plant them in full sun. Avoid overhead watering and keep the bush well-pruned to improve air circulation. Keep the area weed-free and avoid over-fertilization.
This is another fungal disease that affects raspberries and is caused by Didyimella applanata. The fungus spreads through splashing water and wind.
Purple or brown lesions appear on the lower areas of the cane, just below the bud or leaf. The lesions enlarge, and the leaves turn yellow and wilt.
Fungicides can help control the spread. Prune out old fruiting canes right after harvest and destroy them.
Keep the bush pruned to maintain air circulation and prevent overhead watering. Avoid excessive use of fertilizers, especially nitrogen.
Raspberry Leaf Spot
This is caused by the fungus Sphaerulina rubi. The spores are spread through splashing water, either through irrigation or rainfall.
Dark green spots appear on young leaves. As the problem progresses, the spots enlarge, causing the leaves to tan and fall.
Prune out the infected parts of the plant and destroy the debris. In severe cases, spraying fungicides can help manage the problem.
Keep the bush thinned to allow air circulation.
The fungus Phragmidium rubi-ideai causes yellow rust in raspberries. The spores are transmitted by wind, but unlike other diseases, this one will not spread within the plant.
It appears as yellow or orange spots on the underside of the leaves, which may cause the leaves to fall prematurely. The plant becomes more susceptible to cold injury.
Prune out all dead, damaged, and old fruiting canes right after harvest and destroy the debris. If the bush is severely infected, fungicides such as Bonide Liquid Copper Fungicide Conc may help.
Plant resistant varieties such as Sumner or Canby and ensure good spacing between plants to ensure air circulation. Keep the bush sufficiently thinned and keep the area free of fallen leaves and plant debris. Any diseased material should be destroyed.
Botrytis Fruit Rot (Gray Mold)
Botrytis Fruit Rot is caused by the fungus Botrytis cinerea. This remains on infected bushes debris and mummified fruit over winter. Botrytis cinerea then thrives in warm, wet weather.
It appears as a gray or brown mold on blossoms or fruits that enlarge quickly. While the plants may become infected early in the season, symptoms will only appear around harvest time.
Remove and destroy infected berries as soon as you spot them to control spread. Remove and destroy fruiting canes once they’re harvested.
Plant raspberries in full sun, with well-drained soil around them. Remove mummified fruit and plant debris from the surrounding area. This will prevent the disease from overwintering. Keep out the weeds and keep the bushes pruned to maintain air circulation.
Raspberries are also susceptible to certain bacterial diseases. Different types of bacteria that dwell in the soil are spread to the plants through different means. In most cases, splashing water and infected gardening tools will carry the disease to the raspberry bushes. Plants that have been recently pruned and have fresh, exposed wounds are most susceptible.
Erwinia amylovora is the bacterial pathogen responsible for causing fire blight. It’s spread by wind, water splashes, and pests.
The infected portion of the cane blackens and bends over. As the disease progresses, the leaf veins and surrounding tissue turns black, eventually causing the leaf to wither and die. The infected berries turn brown and dry before they have a chance to develop.
Remove and destroy the infected parts of the plants.
Purchase healthy, certified, disease-free plants from a reliable source. Manage pests and avoid over-fertilization. Fertilizers will promote vigorous growth, making the plants even more susceptible to diseases.
Crown and Cane Gall
Crown and Cane Gall is a bacterial disease in raspberries. This is caused by either of the two bacterial pathogens, Agrobacterium tumefaciens and A. Rubi. They reside in the soil or on plant debris and are spread through water, wind, insects, and gardening tools.
It appears as knobby galls on stems, canes, or roots. Young galls are spherical, light brown, and soft, while older ones turn darker in color and woody.
Prune away the infected areas of the cane and destroy them. Treat the wound with a pruning sealer. If the plant still doesn’t recover, it may need to be completely removed and destroyed. When replacing it with a new plant, don’t plant the new canes at the same location.
Plant resistant varieties, and don’t choose plants that show any signs of galling or swelling. Prune the plants during dry weather and disinfect the pruning tools each time you use them.
Several pests may bother your raspberry plants. Well-maintained plants are less susceptible to pests and insects. Even if pests do attack such plants, they have a better chance of recovering from the problem.
Raspberry Cane Borer
If you see the cane tips wilting, you’re most likely dealing with the raspberry cane borer. The cane borer is a small black beetle, about ½ an inch in length and antennas as long as its body. The female beetles chew two rows of holes around the tips of the primocanes and lay eggs in them. When the larvae hatch, they continue burrowing through the holes, down to the roots to overwinter and kill the cane. Trim the wilted canes to at least 5 inches below the start of the hole and destroy the pruned debris.
Red-necked borers cause the canes to swell up around 1.5 inches in diameter. It’s a ¼ inch long bluish-black beetle with a copper-red neck. The female beetle lays eggs in cane barks between late May to early June. White larvae hatch and bore deeper into the cane, causing the branch to swell up. Prune and destroy the canes that show any signs of swelling. Pruning should be done in fall or winter when the plants are dormant. Destroy the pruned debris instead of composting.
Raspberry Crown Borer
If the leaves on your raspberry bushes are turning red, you’re possibly dealing with the raspberry crown borer. Other than damaging the leaves, the pest causes the canes to wilt by late summers. With a white body and brown head, the insect is an inch long and feeds on the larger roots (called the crown) and the base of the raspberry plants. The adult crown borer is a moth that looks like a black and yellow wasp that lays eggs on the underside of the leaves. When the larvae hatch, they crawl down to the roots, where they feed and overwinter. The problem is dealt with by removing the infected canes down to crown level. Destroy plant debris.
Damaged fruit and foliage may suggest an invasion by the Japanese beetle. They feed in clusters, causing severe damage to fruits and leaves. Japanese beetles are ½ inch long with green bodies and copper-brown wings. They are active in warm, sunny weather and begin feeding in June. Handpick and destroy the beetles or spray with insecticides to manage the infestation. Neem oil is also effective against these pests.
We have been through many common raspberry plant problems. I hope this information has been useful. Please leave a comment if you have any questions or need help. It is worth taking the extra time to do your best to prevent diseases before they occur. Healthy, well-pruned, well-maintained bushes are less susceptible to diseases and pest attacks. Always use reliable nurseries and look for disease-resistant varieties. Maintain them well and manage any disease that appears promptly, so the damage is minimal.