Autumn Raspberry Problems

Dear Jeff

I always recommend autumn raspberries because they are generally more pest resistant than summer raspberries and in our case in Stephanie’s Kitchen Garden we have always found the raspberries themselves to be larger and sweeter. Although this doesn’t seem to be the case for you but it sounds like you may have a few things going on with your raspberries.

By the appearance of the yellowing leaves I think your plants have a nutrient deficiency, predominantly nitrogen and potassium. All plants need nitrogen, potassium and phosphorous to thrive, plus various trace elements. Without nitrogen the leaves turn yellow and growth is spindly. Potassium generates good flowering and fruiting and helps ripen wood. Plants lacking potassium tend to have blue, yellow or purple tinted foliage and a poor crop. Without phosphorous, which aids strong roots and shoots, leaves tend to be small and discoloured. The most common trace element deficiencies are manganese and iron, which cause yellowing leaves with brown edges. Although you said you have been feeding with Miracle Grow twice a year I think it would be more beneficial to feed once a year in the spring (ideally March) when the canes are starting to grow. As a guide If your plants have good, thick stems that grow 4 to 6 feet tall, you are fertilising correctly. Maxicrop Original Organic Seaweed Plant Growth Stimulant will give your fruit canes the valuable nutrients they require and aid their general health but it will also help protect them from pests and diseases.

Raspberry canes dislike soggy soil and grow best in light well drained soil – I’m wondering after the wet season we’ve had if your raspberries are suffering because of that. If they are kept too wet for long periods of time, the roots are unable to absorb iron from the soil and the leaves start to turn yellow from lack of iron. Iron chlorosis in raspberries is a common problem, especially in plants grown in clay soils. Plants that are iron deficient are weak, producing small fruit of poor quality and can die from insect or disease problems. I would give your plants a feed of Sequestrene Plant Tonic now (unfortunately Harrod Horticultural do not stock this product but it is widely available from garden centres and online) and improve your soil overwinter by added plenty of well-rotted manure or compost to the soil to improve moisture retention, drainage and soil structure. If you have access to some ash from a log burner you could use this by mulching around the bottom of the plant this will give the plant a good dose of potash which will help with the development of flowers and fruit. You could then top up with Strulch which is excellent for weed retention, keeps moisture in and will gradually break down over time adding valuable organic matter to your soil, we use this regularly on our raspberries in Stephanie’s Kitchen Garden.

On the other hand your plants could be suffering from a viral disease such as Raspberry Leaf Curl Virus. This causes curling and distortion of dark green leaves and the infected plants appear stunted and contain excessive branching. The Infected fruit is usually small, crumbly, and seedy which you say that you have. This disease is spread slowly by the small raspberry aphid. Severe infection causes a reduction in yield, fruit quality, and winter hardiness. Unfortunately there are no chemicals available for the control of virus diseases.

I would improve the soil and feed the plants straight away with Sequestrene and feed with the Organic Seaweed plant growth stimulant in the spring. Try to improve your soil over winter and see what your canes are like next year and if the yield improves. If you see no improvement you may have to destroy the plants and plant replacement canes in a new site. Avoid replanting on the same site to avoid the viral contamination. I don’t know what variety your raspberries are but we have had great success with the autumn fruiting variety ‘Autumn Bliss’.

Good luck and I hope you see some improvement with your plants next year.

Kind Regards

Lynn Burton – Horticultural Adviser

Raspberry nutrient deficiency

For plants to successfully grow, flower and fruit they need nitrogen, potassium, phosphorous and different trace elements. Without one or more of these, plants will start to display physiological symptoms – low nitrogen causes weak, yellow leaves, while a potassium deficiency results in poor harvests and discoloured foliage. Trace elements include manganese and iron, and it’s deficiencies of these that are most frequently encountered, resulting in yellow leaves and brown edges.

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Symptoms

In summer, raspberries fail to thrive, the crop is poor and the leaves have a general unhealthy look.

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raspberries

Organic

Pelleted poultry manure gives a quick boost of nitrogen, while organic compost gives a longer-term solution. Add bonemeal if your raspberries are short of phosphorous. In general, if you’ve added plenty of well-rotted compost to the soil to improve moisture retention, drainage and soil structure, you’re unlikely to have too many problems.

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Chemical

Add sulphate of ammonia for nitrogen deficiency. Sulphate of potash cures potassium deficiency. For low phosphorous levels, apply super-phosphates. Top up manganese levels with iron chelate and use Epsom salts to tackle magnesium deficiency.

Raspberry

Description

Raspberry is the name given to two plant species in the genus Rubus, Rubus idaeus (red raspberry) and Rubus occidentalis (black raspberry) grown for their edible fruit. Raspberry plants have perennial root systems and biennial stems which are known as canes. The canes are woody, erect and shrub-like and generally undergo a period of growth one year and fruit production the next although primocane varieties exist that produce fruit in the first year. The canes may possess spines. Raspberry plants produce white or pink flowers with five petals which are surrounded by green sepals. After the plant has been pollinated, an aggregate berry is produced which consists of numerous druplets which are held together into the familiar raspberry fruit by tiny hairs. Raspberry canes can grow from 0.5 to in excess of 2 m (1.6–6.6 ft) in height and red raspberry will produce a commercial yield of fruit for 16–20 years, while black raspberry has a shorter lifespan and will produce for 4–8 years. Red raspberry may also be referred to as European raspberry, red garden raspberry or hindberry, while black raspberry may be referred to as blackcap raspberry and may have originated in the Ide mountains of Turkey.

Ripe raspberries
Raspberry blossoming
Raspberry cane with new shoot
Raspberry drupelets
Raspberry foliage
Raspberry fruits ready to harvest ‹ ×

Uses

Raspberries are primarily consumed as a fresh fruit or may be processed into jams, jellies, juices and pulp.

Propagation

Requirements Raspberry plants grow best in regions with cool summers and relatively mild winters. The plants are sensitive to high temperatures and grow best when daytime temperatures are around 25°C (77°F). Raspberries are best suited to well-draining sandy loams, rich in organic matter and have a pH between 5.5 and 6.5. Drainage it critical in raspberry propagation as the plants are susceptible to root rot. Plants require full sunlight and should not be planted in low lying areas where water may build up. Raspberries also require a post support system or trellis to support the weight of the fruit on the canes. Raspberry canes are biennial and produce fruit in the second year of growth. Canes in their first year of growth are called primocanes and those in the second year of growth are called fruiting canes or floricanes. The young canes are green in color, whereas the older floricanes are tougher and have a woody covering making them easy to tell apart. Preparation Soil may need prepared up to two years in advance of planting if major amendments are required. Acidic soil can be amended with lime to bring the pH up to a level suitable for raspberries. Organic content can be increased by planting a cover crop or by the addition of manure or compost. Avoid planting raspberries where peppers, eggplant, tomatoes or potatoes have been grown previously as these plants are host to Verticillium fungi which can cause root rot in raspberries. Choose a raspberry variety which is suited to your region. Red raspberries tend to be the most cold hardy, whereas black or yellow varieties are more sensitive. Planting and trellising Many raspberry varieties are very vigorous and using a support system such as a trellis will help to protect the canes from wind damage while also supporting the weight of the fruit crop. The trellis should be constructed before or at planting to avoid damaging the young plants after they are in the ground. The traditional method of supporting red raspberry canes is a post and wire system. This method involves running two wires about 60 cm (2 ft) apart vertically between wooden posts staked into the ground. The lower wire should be positioned 90 cm (3 ft) from the ground and the upper 1.5 m (5 ft) from the ground. The raspberry canes can then be tied to the wires. A second option is a T-trellis which is similar to the post and wire but the vertical wooden posts each have two cross bars to attach the wire. Two sets of wires run parallel to one another, one above the other. The vertical posts should be spaced 3.6–4.6 m (12-15 ft) apart with the lower wire positioned 90 cm (3 ft) from the ground and the upper 1.5 m (5 ft) from the ground. Raspberry plants in the home garden are usually grown from bare root plants or from tissue-cultured plants and should be planted in early Spring when the danger of any severe frosts has passed. The plants are usually planted in a row and the suckers will fill in the spaces to produce a hedge. Plant approximately 70 cm (27.5 in) apart, allowing 2.4–3 m (8–10 ft) between rows. Pruning Allow the raspberry plants to fill in the row to a width of about 30–38 cm (12–15 in) during the course of the growing season. Remove any suckers which are produced outwith this row. After harvest, cut the fruited canes of summer-fruiting varieties to ground level. Select 6–8 of the strongest young canes on each plant and tie them to the supporting wires so that they are spaced 8–10 cm (3–4 in) apart. Cut all of the canes of Autumn fruiting varieties to ground level after harvest. Cut back canes as needed in the summer if required to prevent crowding.

Post and wire trellis system
Raspberries are usually planted in a row and allowed to fill in to create a hedge
T-trellis system ‹ ×
CABI Crop Protection Compendium. (2014). Rubus idaeus (raspberry) datasheet. Available at: http://www.cabi.org/cpc/datasheet/48002. . Paid subscription required. Ellis, M. A. & Converse, R. H. (Eds.) 1991. Compendium of raspberry and blackberry diseases and insects. American Phytopathological Society. APS Press. Strick, B. C. (2008). growing raspberries in the home garden. Oregon State University Extension. Available at: http://ir.library.oregonstate.edu/xmlui/bitstream/handle/1957/18936/ec1306.pdf. . Free to access.

Ministry of Agriculture, Food and Rural Affairs

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Rust diseases on raspberries

There are several rust diseases that attack raspberries. Rust diseases often have complicated life cycles that include alternate hosts, and most produce several types of spores. If you see rust diseases on your raspberry crops, it is important to identify which disease is present, so you can manage it effectively.

Late leaf rust (Pucciniastrum americanum)

Crops attacked: Red and purple raspberries

Alternate hosts: White spruce

Symptoms: Pale orange powdery spores on lower leaf surface, upper surfaces develop small yellow areas that gradually turn brown. Severe infections may result in early leaf drop, reduced plant vigor and yield and increased winter injury to infected canes. On fruit, bright orange powder y spore masses develop on infected drupelets.

Control: Prune and trellis raspberries to encourage air movement and rapid leaf drying. Prune out and remove old canes. If possible, remove nearby white spruce which are required for the disease to complete its life cycle. Prebloom applications of Ferbam to raspberries might help reduce infections. Currently there are no other fungicides registered for control of late leaf rust in Ontario.

Comments: Late leaf rust is common in Ontario. While summer-bearing cultivars often escape fruit infections, fall-bearing raspberries tend to develop fruit infections if weather conditions are favourable for disease development. The cultivars Heritage, Jaclyn, and Caroline seem especially susceptible.

Figure 1. Late leaf rust on raspberry leaves.

Orange rust (Arthuriomyces peckianus and Gymnoconia nitens)

Crops attacked: All raspberry species except red raspberry

Alternate hosts: none

Symptoms: Plants develop symptoms the year following infection. New leaves are stunted, pale and spindly. Bright orange waxy pustules develop on the lower leaf surface, later becoming bright orange and powdery. Infected plants are unproductive.

Control: This disease is systemic – once a plant is infected it is always infected. Remove infected plants, preferably before orange pustules break open and spores spread to more plants. Remove wild black raspberries from adjacent woods and hedgerows.

Comments: Very common on wild black raspberries and blackberries.

Figure 2. Late leaf rust on raspberry fruit.

Yellow rust (Phragmidium rubi-idaei)

Crops attacked: Red raspberries

Alternate hosts: none

Symptoms: In spring and early summer, yellow pustules appear on the upper leaf surface of young leaves. As summer progresses orange pustules are produced on the lower leaf surface, eventually turning black as the overwintering spores are produced. If infections are early and severe, the disease can cause early leaf drop and reduced winter hardiness.

Control: Purchase clean plants from a certified plant grower. Reduce inoculum by pruning out old canes and cultivating to reduce leaf debris. Several group 3 fungicides, such as Nova, Tilt and Bumper, are registered for control of yellow rust. Apply before symptoms appear.

Comments: This disease is not prevalent in Ontario, although it is common in the Pacific Northwest. Yellow spots on the upper leaf surface can help growers distinguish between yellow rust and late leaf rust, which does not produce symptoms on the upper leaf surface.

Figure 3. Orange rust on black raspberry.

Table 1. Rust diseases of raspberry and black raspberry

Common Name (Scientific Name) Crops Attacked Alternate Host Symptoms Control
Late leaf rust (Pucciniastrum americanum) Red and purple raspberry (common in Ontario) White spruce Orange powdery spores on lower leaf surface, and on fruit. No distinct spots on upper leaf, but eventual necrosis. Crop sanitation, trellising and pruning to assist with quick drying. Remove nearby white spruce.
Orange rust (Arthuriomyces peckianus Gymnoconia nitens) All raspberry species except red raspberry None Bright orange waxy pustules develop on the lower leaf surface, later becoming bright orange and powdery. Remove infected plants. This disease is systemic in plants.
Yellow rust (Phragmidium rubi-idaei) Red raspberry (not common in onatario) None Yellow pustules on upper leaf surface of young leaves. Orange powdery spores on lower leaf surface turning black in late summer. Crop sanitation and use of registered Group 3 fungicides in spring and early summer.

Pest Profile: Yellow Rust

By Greg Welfing

Pest Profile is a recurring feature in this magazine. Periodically we pick an agricultural pest to feature and learn more about its biology and control methods.

Yellow rust is a plant disease caused by the fungus Phragmidium rubi-idaei. It is a very common disease affecting red raspberries (Rubus idaeus). It is very prevalent in the Fraser Valley. The only host plant for this disease is red raspberry.

Life Cycle

Yellow rust is predominantly a foliar disease affecting raspberries.

The fungus overwinters as spores (a specific type of spore called a teliospore) on leaf tissue and in the bark of dormant canes. It will progress through a series of spore-producing stages throughout the season. In early spring through early summer, yellow pustules (raised bumps) will appear on the upper surface of the leaves. These start off small and then mature into raised ring-shaped structures, called the aecia stage. This stage is the most conspicuous and is the easiest to notice in the field (figure 1). As the summer progresses, a third spore stage (uredinia) will develop on the underside of the leaf. These spore spots are usually more orange in colour than the yellow aecia stage. In this stage the spread of the disease can be quite rapid. The spread is always faster in cold and wet conditions. The uredinia stage will then develop into the black-coloured overwintering (teliospore stage), completing the life cycle.

Damage

Yellow rust is predominantly a foliar disease. It can infect succulent canes as well, but the primary damage is done to the leaves. In warm years, it can be solely a cosmetic problem, but in wetter years like this one, it can defoliate canes completely if left uncontrolled. If infections happen early and are severe, yellow rust can cause leaves to drop early and reduce the winter hardiness of the plant.

Fruiting laterals can also be infected early in the spring. If this is the case the fruit will die on the plant before maturing.

Management

Proper disease control always starts with having a clean field. Make sure that any new plants that you purchase are from a certified disease-free nursery. Different varieties vary in their susceptibility to yellow rust. If yellow rust is a concern in your fields, try to pick a variety that is less susceptible. In the fall make sure to reduce inoculum by pruning out old canes and cultivating the prunings to reduce leaf debris. While tying up the primocanes in the fall, remember to strip off the leaves. When leaves are left on the plant over the winter, they serve as a source of inoculum for the disease. During the growing season, strive to maximize air flow between the plants. This will help keep the plants dry and help reduce the spread of yellow rust.

There are some chemical control options as well. There are a number of FRAC group 3 fungicides registered for use on red raspberries for control of yellow rust. It is best to apply these products preventatively in spring.

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