Raspberry Plant Problems: Reasons For Raspberry Canes Turning Brown

Isn’t it satisfying to harvest your own raspberries? I love the way a perfectly warm, ripe raspberry rolls off its mount into my fingers. Raspberry aroma is tangy, and the taste of a fresh raspberry is delightfully warm, sweet and tart! Raspberry plants are worth growing. That being said, there are many diseases of raspberry plants so it is good to educate yourself about how to grow the delectable raspberry. Canes turning brown are a common symptom of many different diseases of raspberry plants.

Understanding Raspberry Plant Problems

One of the first things you need to know is the difference between a primocane and a floricane. A primocane is a leafy stalk formed during its first year on a raspberry plant. It may produce buds but doesn’t typically produce fruit. You want to let the primocanes grow and then overwinter for producing flowers and fruit the second year.

During the second year of this cane’s life, it is called a floricane. Floricanes produce flowers and fruit. They typically die or become non-productive after that. You should cut floricanes down to ground level after you harvest your berries. Leaving floricanes uncut can lead to unnecessary raspberry plant problems.

Reasons for Raspberry Canes Turning Brown

Raspberry cane diseases that result in browning can be caused by bacteria or fungi. Browning raspberry canes can also be a sign of normal growth. In general, a floricane is not as lush and green looking as a primocane. It becomes a bit woodier and browner in its second year. This is not a problem.

Bacterial problems

Bacterial diseases include fire blight and bacterial blight. Both of these diseases cause significant browning raspberry canes – very dark or burnt looking stems and leaves are a sure sigh. These diseases can ruin fruit production and are favored by moist, wet springs or winters. They need a wound opening or pruning cut to infect the plant.

It is best to cut out the infected plant material at least 12” below the diseased area. Destroy the plant material. Do not compost it. Copper sprays applied periodically throughout the season can help protect the plant but will not prevent the disease.

Fungal diseases

Some important fungal diseases that lead to raspberry canes turning brown include spur blight, cane blight and anthracnose. Look at your primocanes in late summer or early fall before they harden up for winter to see if you have signs of these diseases.

  • Anthracnose displays round, sunken white to tan colored pits in the internodes of the cane or stem (the areas between leaves or smaller branches). These pits often have a purple margin. The disease weakens and cracks the bark and often leads to death of the cane over the winter.
  • Spur blight initiates its disease course in the leaves or at the node where the leaf attaches to the cane (stem). In the leaves, you’ll see yellowing and browning. The leaves will die and drop off leaving the leaf petiole. On the branch stem, you’ll see little ½” purple or brown spots around the nodes. These spots might expand around the entire stem. During the next year, these areas will be non-productive and appear leggy.
  • Cane blight is caused by wounds in the stem. The wounds form reddish-brown streaks and can eventually girdle the entire cane causing cane death.

All three of these fungal diseases of raspberry plants are spread from cane to cane rather than root to cane. They love moist conditions. The diseases may overwinter on the plant and then spread from floricane to primocane. Splashing water spreads transmits the fungi in all three of these diseases. Wind also spreads the fungi of spur blight. The keys to controlling these diseases are:

  1. Reduce moisture and humidity in the area
  2. Keep your rows narrower than 18”
  3. Remove non-productive floricanes every year
  4. Don’t prune if you expect rain in the next 5 days.

In severely infected patches, you can mow the whole area down and start over and/or apply an appropriate fungicide. Note that you may be applying a poison to an edible crop if you use a fungicide. Check the label carefully.

If you are starting from scratch with your raspberry patch, be sure to look for disease resistant varieties. Make sure your patch gets enough sun, regular water and is amended with compost every year.

Raspberry Leaf Spot

Overview of raspberry leaf spot

Raspberry leaf spot is perhaps the most common raspberry disease we see in the clinic.

Raspberry leaf spot symptoms

Disease cycle of raspberry leaf spot

Raspberry leaf spot is caused by a fungus called Sphaerulina rubi. This fungus overwinters on leaves and canes which then serve as sources of infection in spring. Young leaves are highly susceptible to this disease, but older spots or lesions produce spores that are readily spread by rain or wind to new tissues throughout the entire season.

Signs and symptoms of raspberry leaf spot

Early infections look like dark green circular spots on new leaves. As leaves get older, spots become light tan to gray. Severe infections cause leaves to fall off in late summer and early fall and this may not only reduce your raspberry harvest, but it also makes plants more prone to winter injury. For pictures, please click on the “Raspberry Leaf Spot” link to the right.

Type of Sample Needed for Diagnosis and Confirmation

The Iowa State University Plant & Insect Diagnostic Clinic can help you to investigate and confirm if you plant has this disease. Please see our website for current forms, fees, and instructions on collecting and packing samples. Contact information for each states diagnostic laboratory for U.S. residents. If your sample is from outside of Iowa please do not submit it to the Plant & Insect Diagnostic Clinic without contacting us

Management of raspberry leaf spot

Cultural measures that increase air circulation are probably the most effective way to control this disease. Since this fungus thrives under high humidity conditions, promoting faster drying of leaves and canes after rain can reduce the chances of infection. The easiest tactic is to start off with properly spaced plants between and within rows, and in established plantings, avoid too many canes per plant. Also, reduce the sources of infection by pruning out old fruiting canes and removing them from the field.

A fungicide program for Gray mold can be effective to control this disease. Also, timing applications and product recommendations can be obtained from the “Midwest Small Fruit and Grape Spray Guide”.

Hello. I have an established raspberry patch of 4 years which has had fairly decent berry production in past 2 years. It is in a low-lying ravine area that frequently floods, which I now understand is the worst place for them. Soil is rich and drains ok, has a slight bit of clay. In May 2018 we had 50 year HISTORIC flooding in Southwestern Michigan which actually collapsed roads. This ravine and raspberry bushes had 10 feet of STANDING WATER FOR 24 – 48 HOURS AND RASPBERRIES WERE COMPLETELY SUBMERGED. The patch was covered in a thick mud that would not wash off, even after spraying and weeks. I removed many of the due to spotting and what appeared to be rot. Over the summer, new growth emerged lower, and appeared to be ok. I trimmed ALL of the branches with wilting and spot, and now — even in September 2018 — much of the new growth continues to develop spotting. I am wondering if the ground is contaminated. Even new plants which we got from another location, and planted in a new row 5 feet over, are showing spotted leaves. Can this be saved? I will start a new patch in higher, better draining ground with new plants- but would like to save this patch! Please tell me what to do. Do I need to treat the ground for contamination? I will contact the county and find out if the standing water contained sewage or not. Thank you so much.

Blackberry (Rubus spp.)-Virus Diseases

See:

Raspberry (Rubus spp.)-Crumbly Fruit

Raspberry (Rubus spp.)-Viruses

Cause Many viruses have been found in blackberries in the Pacific Northwest. Blackberry calico virus (a carlavirus) is universally present in older commercial ‘Thornless Loganberry’ fields. Despite no know vector (other than grafting or vegetative propagation of infected plants) the disease spreads rapidly in the field. Similar calico diseases occur in field-run ‘Marion’, ‘Chehalem’, ‘Olallie’, and ‘Waldo’ blackberries. Other virus diseases known to infect blackberries in the Pacific Northwest include Strawberry necrotic shock virus, (SNSV) an ilarvirus transmitted by unknown means, and Raspberry bushy dwarf virus (RBDV), which infects pollen and is therefore transmitted by insect pollenators. RBDV was found in 4 of 32 fields surveyed in 2000. SNSV is transmitted by thrips in strawberry and there is some evidence it can be transmitted by thrips to Rubus spp. since there can be low levels of transmission in plants that are not flowering. Strawberry necrotic shock virus and Raspberry bushy dwarf virus can be detected serologically.

Other viruses, of lower importance, that can infect blackberry include Apple mosaic virus. There are at least 12 additional viruses that are common in the Southeastern US in blackberry. Each of those viruses is symptomless in single infections, so laboratory testing must be carried out to ensure that these viruses are not introduced into the PNW.

Symptoms Usually no definite symptoms are observed. Symptoms are quite variable depending on cultivar and virus combination. Degree of crumbliness or druplet abortion can range from severe to very mild. Yellow line patterns are common on plants infected with Blackberry calico virus (almost as if painted on with a fine brush) and general chlorosis in plants of ‘Marion’ blackberry infected with Raspberry bushy dwarf virus (as if painted on with a sprayer). Strawberry necrotic shock virus (usually symptomless alone) or Blackberry calico virus cause minor impacts on fruit yield and quality. Raspberry bushy dwarf virus in ‘Marion’ causes bright yellowing of the leaves on primocanes and a bleaching of leaves on fruiting canes in July and August. Chlorosis has not been observed early in the season. A 50% yield reduction and 40% reduction in fruit size and druplet number have been measured. Since the receptacle stays with the fruit, the crumby berry symptom is not observed. No reduction in cane diameter or length was observed. RBDV in mixed infections with BRNV and/or Blackberry calico virus can cause drupelet abortion and misshapen fruit, though it has been much less of a problem in blackberry than in red raspberry.

Cultural control A control program for blackberry viruses must begin with nursery stocks propagated from virus-indexed sources known to be fruitful. Such sources are commercially available.

  • Use certified planting stock.
  • Plant immune or resistant cultivars if available.
  • Plant in large blocks to slow movement of pollenborne viruses into new plants, especially if fields in the immediate area are infected.
  • Test for nematodes before planting and do not plant in soil containing Xiphinema spp.

Raspberries and cultivated blackberries: Pests and diseases

Note Number: AG0570
Published: November 1996
Updated: December 2011 and August 2013

This Agriculture note lists the common pests and diseases of Rubus crops in Australia. It is not a comprehensive list of all rubus diseases found worldwide, nor a full description of the life cycle of disease organisms. Life cycles of all major and minor rubus diseases can be found in Compendium of Raspberry and Blackberry Diseases and Insects edited by Ellis, converse, Williams and Williamson; 1991, APS Press, St Paul, MI, USA.

Virus diseases

Raspberry Bushy Dwarf Virus (RBDV) – is the most common virus disease reported in rubus crops. It is transmitted by pollen, and therefore spread by bees and other insects which forage in flowers. Symptoms are yellow flecks or splashes on leaves, and poor drupelet set causing crumbly malformed fruit. The yellow leaf colouration, when observed in raspberries, appears as if touched quickly with a paint-brush. It is a distinctive yellow colouration rather than the more common pale cream-yellow caused by sucking insects or senescence. Some raspberry cultivars are immune to infection by RBDV, and in others infection is symptomless. Willamette is the only immune raspberry cultivar grown in Australia. The condition is symptomless in some blackberries and Loganberry, however yields and cane growth of Loganberry are seriously reduced. Virus diseases are incurable in the field. Infected plants should be destroyed, following identification of the disease organism. The only safeguard against virus infection is to begin with clean plants supplied by an approved plant health scheme.

Fungal diseases of fruit

Grey Mould – caused by the fungus Botrytis cinerea, is the most serious berry disease found both in Australia, and worldwide. Symptoms are a grey fungal growth, frequently affecting only a few drupelets, and then more commonly at the aperture end of the fruit, at the “collar”. Grey mould is distinguished by growth of short grey “fur”, which grows rapidly in wrapped punnets. Infection begins during flowering, and remains latent in withered floral parts. Infection occurs via the stigma and style, and stamens. It is exacerbated by cool wet conditions, from flowering onward. It is important for management of the disease to encourage free air movement around fruit and accelerate drying after rain. This can be done by keeping primocanes separate from fruiting canes, by keeping row bases clean and narrow, and by favouring cultivars which present fruit well Spores are present throughout the year, as the fungus also attacks canes, dead leaves and other decaying vegetation. Alternate year cropping can reduce the background level of inoculum by removing all canes in the winter after harvest. Cultivars vary in their susceptibility to grey mould both on the plant, and post-harvest. None can be regarded as being resistant to grey mould. Correct post-harvest handling of fruit is essential for the suppression of grey mould. Complete eradication from a crop is not an option, and all fruit should be treated as susceptible to rot, given conditions favourable for disease.

Fruit Anthracnose – caused by the fungus Elsinoë veneta, causes a hard grey patch on the top of drupelets, around the point where the style meets the fleshy skin of the drupelet. When it occurs, it is frequently found only on one side of fruit, or facing one direction. It is exacerbated by rain during ripening. It is distinguished from the more common grey mould by the absence of hyphae, which give grey mould the appearance of short “fur”. Cultivars differ in susceptibility; it is rarely reported from Willamette, Chilcotin and Meeker raspberries, but Skeena is susceptible.

Fungal diseases of canes and foliage

Cane anthracnose – incited by the fungus Elsinoë veneta, causes blotchy purple and grey lesions on the primocanes of raspberries, Loganberries, and blackberries. Lesions start as circular purple spots in late spring. As the disease progresses, lesions enlarge to less regular shapes and the middle turns grey, leaving a purple margin. The economic loss caused by this condition is unknown; if wet weather spreads it to fruit, losses can be considerable. Its severity is reduced by alternate year cropping. Copper oxychloride – based sprays are registered for chemical control. Preventative spraying should commence during winter, when canes are dormant.

Raspberry yellow rust – is caused by the fungus Phragmidium rubi-idaei. It appears firstly as yellow – orange pustules on the upper side of raspberry leaves, in spring. Later in the season orange-yellow spots appear on the under-side of leaves, and these turn black as the fungus life-cycle progresses. The condition is exacerbated by cold wet weather; warm, dry weather will halt the spread of the disease. Cultivars differ in susceptibility. The spores (teliospores) overwinter in cracks in the bark of dormant canes. Alternate year management will reduce background inoculum. Yellow rust is usually regarded as a cosmetic problem only, however it can defoliate canes if prolonged wet weather in spring encourages rapid development. It is not seen on blackberries. Copper oxychloride – based products are registered for use against leaf rust.

Blackberry rusts – may be caused by several fungi. The biocontrol agent Phragmidium violaceum can infect the late season thornless blackberries and wild or weed blackberries; the trailing blackberries, and erect blackberries are less susceptible. Symptoms begin with yellow-red blotches on the upper leaf surface, which darken to red-purple spots with yellow or brown centres. Powdery yellow pustules develop on the under-side of leaves, directly below the spots on the upper surface. The pustules change colour to black over a period of weeks. The fungus requires cool moist conditions and invades young tissue.

Septoria leaf spot – caused by the fungus Septoria rubi, causes evenly-shaped lesions on blackberry canes and leaves, usually with a whitish centre and purple-brown margin. It does not attack raspberry plants. Damage is more severe following prolonged wet periods and control begins by encouraging foliage to dry quickly after rain, such as by avoiding training into bundles or excessively dense patches of foliage.

Cane and leaf rust – caused by the fungus Kuehneola uredinis affects blackberries, producing yellow or orange spore bodies on stems and the undersides of leaves. Kuehneola can be distinguished from Phragmidium rusts by the absence of prominent red-brown spots on the upper surface of affected leaves.

Root diseases

The most severe and common root disorders found in Australia are caused by fungi. In the last fifteen years, Phytophthora root rots have become the single most serious soil-borne raspberry pathogen in all raspberry – growing areas of the world.

Phytophthora root rot – caused by Phytophthora cryptogea and possibly other species of Phytophthora, has been more frequently reported in Australia in the past ten years. Blackberries and hybrids appear to be resistant or immune to Phytophthora. Affected raspberries gradually lose their roots, starting with the fine white feeder roots which form in late winter – spring, and progressing to the larger structural roots. Symptoms vary, but all relate to loss of a functional root system. Most commonly, floricanes die after bud burst; this may occur as leaves expand, or as laterals elongate, or as fruit ripen. Leaves show marginal scorch and browning (necrosis), usually a loss of colour (chlorosis) just inside the necrotic region, and sometimes a reddening in patches inside the chlorotic region. Primocanes may not be affected in floricane-fruiting cultivars, or alternatively they wilt, and then die, showing the same necrosis as seen in floricane leaves. The same symptoms can be observed in plants killed by drowning in waterlogged soil. Control begins by avoiding wet soils which allow production and dispersal of infective propagules, by amelioration of soil structure pre-planting, and by ridging or hilling rather than planting on flat beds. Raspberry cultivars vary in their susceptibility to Phytophthora and to different species of Phytophthora. Cultivars reported resistant in Europe are not always resistant in Australia, and vice versa.

White Root Rot – is caused by a species of Vararia, and is characterised by the presence of sheet-like masses of white hyphae on roots and crowns of raspberries and blackberries. Affected plants wilt and die. They may yellow, and initial symptoms can include poor lateral development and small leaves, before the severity of the disease becomes obvious. The disease is most severe in warm dry soils. It may survive on roots and branches of forest trees remaining in the soil following clearing. It is spread by direct root contact and usually spreads only slowly. Control measures include not allowing soil to dry out and speedy removal of afflicted plants. Replant sites should be fumigated.

Armillaria – Arimalia species cause death of rubus plants with similar symptoms to other root-rotting fungi. Armillaria are associated with dead and rotting wood left in the soil from forest or orchard clearing. The fungal growth is characterised by white or yellowish mycelial sheets on the main roots and crown, under the bark. They are easily confused with Vararia, and expert identification should be sought prior to undertaking control measures. They can persist for many years and are very difficult to control. Eradication relies on removal of dead and dying plants plus any other wood which may be a source of disease in the adjacent area. In autumn, some Armillaria fungi produce fruiting bodies characterised by a yellowbrown cap, known as honey fungus.

Crown Gall – is a bacterial disease transmitted by Agrobacterium rubi and Agrobacterium tumefaciens. A.tumefaciens has a wide host range including many Rosaceous crops, such as pome and stone fruits, and grapevines. The condition causes growth of large lumps of tissue, with either a smooth bark-like exterior or a rough callus-like appearance. Galls form at soil level on blackberries and hybrids, and may be totally buried on raspberries. They may be as large as a grapefruit. The galls are produced by cells of the host plant into which the bacteria has transmitted a piece of its own DNA known as a plasmid, which programs the host cells to produce specific nutrients required by the bacteria. Once a plant is infected the condition cannot be eradicated. Control measures rely primarily on nursery and farm sanitation. Nursery stock should be bought from a high health source and plantations should be prepared using green manure crops to break the linkage between host plants. A modified strain of A. tumefaciens known as A. radiobacter strain K84 is used by fruit tree nurseries to protect plants from invasion by A. tumefaciens, however it is not reported to protect host plants from A. rubi infection. The bacteria requires a wound site to enter the host plant and infection is hastened by nematode damage.

Pests

Two-spotted mite (Tetranychus urticae) – also known as spider mites, are minute arthropods found in warm weather on the underside of plant leaves. They look like very small spiders, with an oval body marked on the upper side with two prominent spots. They are more commonly found on raspberries than blackberries. Their feeding ultimately causes pale spots to appear on the upper side of leaves, which can become a silver sheen, and can cause leaves to “burn” in hot weather. In low numbers they cause little damage but in large numbers they reduce growth and the quality of buds formed for next season’s crop. They have a wide host range and for this reason reliance solely on chemical controls is of little use. They may be controlled under most circumstances by predatory mites which eat the pest mites, plus chemicals registered for control of mites at either the adult or egg stages. Two spotted mites are mainly a problem where large crops of other host plants are present or where extensive insecticide spraying has removed their natural enemies.

Dried fruit beetle (Carpophilus spp) – is an occasional pest found in raspberry fruit. Adults are up to 3 mm long, brown or black, with a narrow, fattened oval shape. The thorax is almost flattened cylindrical in outline and the wing cases finish before the end of the abdomen. They are more a pest of drying and rotting fruit, but their feeding habit of climbing inside raspberries makes them hard to control and easy to overlook. No insecticides are registered for use against Carpophilus in raspberries. They should not be confused with Stethorus beetles, which are also brown or black, but are smaller (up to 2mm long) and almost hemispherical. Stethorus beetles are an important predator of thrips and mites, and are related to ladybirds.

Looper caterpillars – are the larvae of the light brown apple moth, Epiphyas postvittana. Their prevalence varies considerably from one season to another. The adult moth is buff coloured, with a wingspan up to 18mm, and hides under foliage during the day. The caterpillars start life very small and yellow, changing to green as they enlarge up to 18mm before they pupate. They wriggle quickly when disturbed, or fall or hang suspended from a thread like spider web. They feed on leaves, and roll leaves to hide and pupate. Their main damage to raspberries is cosmetic, when they climb to the top of freshly picked fruit. They occur more on raspberries than blackberries. Control mainly depends on not killing their natural enemies. Pheromone mating disruption techniques are being developed for use in apples, and may be appropriate where serious outbreaks occur regularly.

Earwigs (Forficula auricularia) – are recognised by a prominent pair of forceps on the end of the body. Adults may be up to 12 mm long. Although they have wings they rarely fly, preferring to run and hide when disturbed. They are nocturnal. Damage is mainly seen in raspberries, where they chew into drupelets from the point of stylar insertion, leaving the drupelets hollowed out with the seeds half exposed. Control is best affected by not leaving hiding places for them, such as loose straw mulch. They can be trapped by leaving upturned flowerpots under the crop plants. Consult your farm chemical supplier for chemicals registered for use on the ground around the crop.

Green Vegetable beetle (Nezara viridula) – attacks raspberry fruit by sucking sap, causing drupelets to shrivel. The adult is green, shield-shaped, about 15 mm long, and releases a stink when disturbed. The nymphal stages look like small adults but with a range of green, yellow, brown and black markings. Control mainly relies on clean farm management to minimise weed populations. No chemicals are registered for use against these pests in rubus crops.

Plague Thrips (Thrips imaginis) – cause damage to flowers by sucking all flower parts. They are slender insects, up to 1.2 mm long, and are best detected by shaking flowers upside-down over a sheet of paper or white handkerchief; alternatively, they can be made to run around inside flowers by gently breathing warm air into the flower. They look like bristles cleaned from a shaving razor, except that they move. They may cause total loss of youngberry crops if not controlled. They seldom damage Silvan blackberry flowers, and more commonly damage Silvan blackberry and raspberry fruit by sucking the drupelets adjacent to the calyx, producing a speckled silver appearance. Control starts with weed free plantings, however they migrate on the wind over large distances. Extreme care must be used if they must be sprayed, as they normally occur at the time when bees are doing their work.

Dock sawfly (Ametastegia glabrata) – is occasionally seen in raspberries, where it bores holes in primocanes late in the growing season, causing growth above the entry point to die. The adult is a small fly, up to 10 mm long, with a narrow dull black body and the wings held at an angle like a European wasp. Control relies primarily on farm hygiene, specifically by removing dock weeds which act as the primary host for the dock sawfly.

Rutherglen bug (Nysius vinitor) – The adult female is about 5 mm long, grey-brown, with a narrow body, and black eyes. The male is smaller and darker. Adults have two pairs of wings, the lower being silvery and the shorter, upper pair are darker silver with dark lines on the trailing edges, which produce an inverted Vee marking on the insect when the wings are folded. They have a wide host range and are strong fliers, and migrate in swarms. They can arrive suddenly in large numbers and suck sap from fruit and leaves. Their numbers are strongly influenced by weather, being most prevalent in dry spring weather following wet winter.

Fruit tree borer (Maroga melanostigma) – is a native moth which primarily attacks a range of fruit and shade trees. Raspberries and willows are occasionally attacked. Damage is caused by the larvae boring into mature raspberry primocane stems, causing them to snap during training or fruiting. The larvae tunnel into the stems, and feed nocturnally on the bark surrounding their entrance. They produce frass which is held in a thin tough webbing and which may girdle the stem. Should the problem be extensive or occur over more then one season, control should start with either removing or treating their major hosts in the area, such as plums, or black wattle trees.

Nematodes

Nematodes are microscopic creatures which cause damage to plant roots. They cannot be seen with the naked eye, and expert diagnosis is necessary to confirm their presence. The most common, Pratylenchus penetrans, has a wide host range including many pasture species. Nematodes are associated with decline of raspberries through feeding on the roots, with the spread of certain viruses (nepoviruses) and also with damage allowing crown gall to invade plants. Typically, damage is seen as a non-specific decline in vigour, and failure to respond to fertiliser or irrigation. Poor areas gradually extend down-hill as the nematodes migrate in soil water. Small numbers can co-exist with raspberries without causing symptoms; in North America, a count of 500 nematodes per 500 cm2 of soil is regarded as the economic damage threshold. Control relies on clean farming practices, as once they are established they are hard to eradicate. Planting nursery stock from highhealth sources, and planting into well-prepared soil that has been prepared by green manuring and fallowing are the best means of control. Plan field drainage to minimise water flow through the soil in winter.

Slugs and snails

Slugs and snails can cause damage to Rubus crops, more commonly to raspberries than blackberries. Control begins with rigorous weed control. If they persist, slug and snail killer may be spread on the ground under the crop. Consult your farm chemical supplier for products registered for use in raspberry and blackberry crops.

Birds

Birds can cause total devastation of Rubus crops if you are unfortunate enough to grow the only food source available. Blackberries are more commonly affected than raspberries. Bird predation is so specific to each farm and its surrounding ecosystem that general warnings cannot offer much advice. In areas adjacent to cities, the imported nuisance birds such as mynahs and starlings are the dominant pest species, but in more rural areas several native birds, notably parrots and cockatoos, can be a serious threat. If the problem is severe, the only proven remedy is to net entire crops. It is most important to net before birds start feeding; once they have developed a taste for a crop they will try hard to find access through holes in nets, and they seem to have all day to spend looking for a way in.

Physiological disorders

Sunburn and white drupelet disorder are both caused by high levels of sunshine, particularly following cool overcast weather. Heritage raspberry appears most susceptible, but the late-season thornless blackberries also suffer. Affected raspberry drupelets turn white as if bleached, and affected blackberry drupelets appear pink and cooked. The only avoidance measure is to erect shade – cloth.

Effects of plant management on disease

Most of the foregoing notes on Rubus pests and diseases refer to farm hygiene as the area where control begins. In some areas where the plague insects do not occur in large numbers, it is entirely possible to grow rubus crops without recourse to chemical sprays. In others, only copper oxychloride-based winter protectant fungicides are necessary. Control begins with clean farming practices. These include:

  • pre-planting land preparation
  • bed formation and land drainage
  • high health nursery stock
  • rigorous weed and sucker control
  • primocane management to optimise air-flow through the canopy
  • management of areas adjacent to crops
  • thorough, regular harvesting to avoid leaving over-ripe fruit
  • proper post-harvest cooling and handling of fruit
  • proper calibration of spray equipment and adherence to recommended rates of chemical use
  • timely and minimal use of pesticides
  • observance of natural predators and minimal disruption to their populations

“If you kill the predators, you inherit their work”

Acknowledgements

This Agriculture note was developed by Graeme McGregor, Mark Whattam and Bill Washington of FFSR in July 1996.

It was reviewed by Mark Hincksman and Neville Fernando of Farm Services in December 2011 and August 2013.

Abstract:
Electron microscopy of ultra thin sections of leaves of symptom less ‘Himalaya Giant’ blackberry and of the virus indicator species, Rubus macraei, showing severe leaf curl symptoms following graft inoculation with scions from this blackberry material, detected highly flexuous virus-like particles with an unusual ‘beaded’ structure. Such particles were restricted to a few vascular cells and were distinct from P-protein common in some such cells. They also appear to be unlike any other structures observed in thin sections of other plant material and those of any other plant virus. The name, Hawaiian rubus leaf curl virus, is proposed because of the consistent association of these beaded particles with symptoms in the Hawaiian species R. macraei. It symptomlessly infected a wide range of Rubus species and cultivars. In a field trial of cultivars of blackberry and hybrid berry near SCRI, plants of ‘Bedford Giant’ blackberry showing diffuse chlorotic line-patterns and ringspots, contained a mechanically transmissible virus that has several properties in common with ilarviruses and in Western blots reacted very weakly with antiserum to Prune dwarf virus but not with antisera to Apple mosaic virus or to Tobacco streak virus.

Raspberry Pests & Problems

Common diseases of raspberries & solutions

There are some common diseases that can affect raspberries, but these can mostly be controlled if they appear.

Raspberry Viruses

Probably the worst and most difficult problem of raspberries as viral infections are incurable. The only solution is to grub up the plants and burn them.Replace with fresh stock and do not plant in the same place.

It is important to buy stock that is known to be free of viruses, as once infected, the canes lose vigour and crops are much reduced. Viruses are transferred from infected plants by aphids, leafhoppers or nematodes.

Symptoms are yellow mottling of leaves or stunted growth. There is no effective control and infected plants should be removed as soon as they are no longer productive. Making sure that weeds do not grow nearby is one way of reducing the possibility of infection, as many of the viruses live in other host plants, many of which are weeds.

Raspberry Rust

Raspberry Rust shows as small pustules on the leaves, starting yellowish, turning orange in the Summer and being black by the end of the season. The easiest way to control the disease is to pick of and destroy and infected leaves, and clear up all fallen leaves in the Autumn to reduce the chances of the disease carrying forward into the next season. Bayer’s Fruit & Vegetable Disease Control is effective against rust.

Raspberry Cane Blight

Raspberry Cane Blight is a serious fungal disease which enters the canes through small wounds and leads to die back of the cane. The first symptom is dead leave sin the summer, followed by a dark brown base to the cane, which becomes very brittle. Bayer’s Fruit & Vegetable Disease Control may be effective, but if the disease is widespread the canes will need to be replaced.

New canes should be planted in another part of the plot, or soil replaced.

Raspberry Spur Blight

Raspberry Spur Blight is a fungal disease where canes develop purple patches and become less productive. Ensuring canes are not overcrowded helps prevention, and again the above mentioned product can be an effective control.

Raspberry Leaf & Bud Mite

Raspberry Leaf & Bud Mite results in yellowish patches on the upperside of the leaves in May, when these mites emerge and canes may develop mis-shapen leaves towards the top. These symptoms are caused by the microscopic mites sucking the sap of the leaves. There is no chemical control, but affected canes usually produce a good crop.

Raspberry Beetle

Raspberry Beetle Image © Entomart

Raspberry beetle can lead to small dry patches in the fruit towards the stalk end, and sometimes small grubs (6-8mm in length) inside the fruits.

Fruits setting later in the season are rarely affected. If they are a major problem, they can be controlled organically with a pheromone trap, which attracts the male beetles and takes these ‘out of circulation’ or with a spray containing deltamethrin as soon as the first pinkish fruit is visible , and then again two weeks later (Leave seven days before picking any fruit)

Hoeing in spring and summer will bring pupae to the surface and expose them to the birds and other predators, reducing there numbers.

Further Information on Raspberries

Growing Raspberries – How to Grow Raspberries

How to Grow Raspberries – A Guide to Growing Raspberries Raspberries Raspberries (Rubus ideaus) are a self fertile cane fruit which prefer a slightly acidic soil, which drains well. They are prone to root rot in waterlogged soil, and dislike really…

Raspberries Seed & Plants

  • Raspberries from the Allotment Shop

Raspberries pests & diseases

APHIDS aka Greenfly will cause distorted and curled new leaf growths. Light infestations may not cause too much of a problem but heavier infestations weaken the canes and compromise cropping production. Either scenario should not be tolerated because greenfly spread viruses and other diseases so it’s a good idea to eradicate them. Soapy water can be used on small colonies and modest planting area’s, otherwise opt for a good insecticide.

VIRUSES can be identified by stunted canes and leaves which are mottled or streaked, usually yellow. Unfortunately there is no cure so all canes should be dug up and burnt. Replanting should occur as far away as possible to prevent the disease spreading to them. If this is not possible and you have to re-plant in the same spot then remove the soil to 2 spits depth replacing it with uninfected soil. You can, as an alternative treat the existing soil with jeyes fluid but you will then need to leave the area fallow for 6 months preferably before planting the new canes. Some varieties are less prone to virus than others, but there are none that can truly be described as virus resistant.
Virus is relatively uncommon and some deficiencies can give similar symptoms so check first or apply fertilizer rich in magnesium and trace elements before assuming the worst.

PHYTOPHTHORA raspberry root rot. More of a problem on heavier soils but not exclusively so. Some varieties are more susceptible than others. Symptoms are that the canes die from the base up, upon lifting the roots beneath have deteriorated and simply rotted away. The disease is spread by water and is becoming an increasing problem amongst commercial plantations, and now it is appearing in private gardens too. There are some fungicides that can treat the problem but these are only currently available to commercial growers and not authorised for use in gardens. The only course of action is to follow the re-plant instructions as for virus above and choose a resistant variety of which there is a limited range – Cascade Delight and Glen Ericht being prime examples.

SPUR BLIGHT is identified by the withering of the new canes as they appear in spring; purple blotches can be seen on shoots and stems. Infected canes should be dug out and destroyed, and remaining growth sprayed with benomyl or a good currently available alternative.

RASPBERRY BEETLE Is the culprit when you have grubs in the fruits themselves. It is quite easily eradicated on a season-by-season basis but timing is crucial. A good systemic insecticide will work but it should be applied at fruit set, and again just as the first berries begin to show some colour.
In all cases of insect infestation Provado is our recommendation. It is readily available from stores and online and it is systemic. This means that whilst it does kill on contact, it is also absorbed by the plant so it works from within, ensuring protection for up to 6 weeks.

Yard and Garden: Handling Issues with Raspberry Plants

AMES, Iowa – Raspberries are popular with many home gardeners. They’re easy to grow, and perform well in much of Iowa. However, gardeners can run into issues with heat, weeds and pruning that curtail yields.

ISU Extension and Outreach horticulturists can help answer your questions about how to best handle raspberry plantings. To have additional questions answered, contact the ISU Hortline at 515-294-3108 or [email protected]

Should I water my raspberries during dry weather?

Adequate soil moisture levels are necessary throughout the growing season for good raspberry production. However, the most critical time for moisture is from bloom until harvest. During fruit development, raspberries require 1 to 1½ inches of water (either from rain or irrigation) per week. Insufficient moisture during this time may result in small, seedy berries. During dry weather, thoroughly water raspberry plants once a week.

Soak the soil to a depth of 10 to 12 inches. If possible, avoid wetting foliage and fruit to reduce the risk of disease problems. Soaker hoses and drip irrigation systems are excellent ways to water raspberries. If overhead watering is unavoidable, water raspberries early in the morning. Morning applications reduce the amount of water lost due to evaporation and allow the plant foliage to dry quickly.

How do I control weeds in my raspberries?

Cultivation, hand pulling and mulches are the most practical weed control measures for home gardeners. Cultivate the raspberry planting frequently during the spring and summer months. Small weed seedlings are easily destroyed. Large weeds are more difficult to control. To prevent injury to the roots of the raspberry plants, do not cultivate deeper than two to three inches.

Possible mulching materials include straw, chopped cornstalks, sawdust, wood chips, dry grass clippings and shredded leaves. The depth of mulch needed depends on the material used. On well-drained soils, the optimum depth ranges from three to four inches for fine materials, such as sawdust, to eight to 10 inches for straw. Avoid deep mulches in poorly drained areas to discourage root diseases. Since organic mulches gradually decompose, apply additional material each year to maintain the desired depth.

Is it necessary to prune raspberries in summer?

Pruning raspberries in summer helps control diseases. It also helps maximize next year’s crop.

After the last summer harvest, promptly remove the old fruiting canes of red, purple, and black raspberries at the soil surface. To help reduce disease problems, the pruned material should be removed from the garden and destroyed.

Pinch out or cut off the shoot tips of black and purple raspberries when the new growth reaches a height of 36 to 48 inches. Remove the top three to four inches of the shoots. Removal of the shoot tips encourages lateral shoot development and increases the fruiting surface area, resulting in higher yields.

Since the new shoots will reach the specified height at different times, go over the planting approximately once each week between late May and late July. Discontinue shoot tip removal at the end of July. Canes that develop after July are small, weak, and unproductive. These small, weak canes can be pruned out the following spring.

Raspberry Leaves Curling – How To Prevent Raspberry Leaf Curl Disease

A typical day in the garden can be ruined by the appearance of a stray insect that leads you to the discovery of an infestation, or worse, a few discolored, curled leaves and the dawning realization that your raspberry plants have contracted raspberry leaf curl virus. Unfortunately, leaf curl disease is much more than a cosmetic problem — the curled leaves on raspberries are an early clue that your plants have a deadly disease.

Raspberry Leaf Curl Virus

Raspberry leaves curling is just one sign of raspberry leaf curl virus, an incurable disease vectored by the small raspberry aphid (Aphis rubicola). Leaves will change, sometimes dramatically, during the early stages of infection. Often, they arch stiffly or curl downward and change colors; red raspberries usually develop yellow leaves, while black raspberries turn very dark green, with a greasy appearance.

As the disease progresses, the canes may also stiffen and become brittle, and fruits mature small, seedy and crumbly, making them inedible. A mild infection may go unnoticed for the first season, but a severe case of leaf curl disease visibly reduces yields and decreases the winter tolerance of your plant. You may find your canes die back considerably more than usual while they’re dormant. Raspberry leaf curl virus can kill a raspberry stand in two to three years and cannot be cured.

How to Prevent Raspberry Leaf Curl

If there are already curled leaves on raspberries in your garden, and other signs of leaf curl disease are emerging, you need to remove and burn or double bag infected plants as soon as possible. There is no cure or treatment for this disease and by removing infected plants, you may save clean plants nearby.

Before replanting your raspberry stand, remove any wild caneberries nearby, as well as neglected brambles. Purchase certified, virus-free nursery stock from a reputable supplier when you’re ready to plant again. Make sure that you clean your tools well before removing the new raspberries from their pots, to prevent transmission of virus from infected plants to your clean stock via shovels and pruners.

Sticky cards help you monitor for aphid activity once your raspberries are planted. These pests are easily sprayed from leaves with a garden hose, or you can spray weekly with insecticidal soap to knock down any aphids on the plant, visible or not. Harsher pesticides are sometimes used, but these will destroy the beneficial insects that may be your best defense against aphid activity.

If your plants are very valuable or you’re raising just a few bushes, you may want to consider installing a screen house around your plantings. Using a screen with a very fine mesh will prevent new aphids from entering the area and keep commercially available aphid predators, like lacewings or ladybugs, close to your crop. If you decide to use beneficial insects, make sure they have an alternative food source and water supply.

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