Boysenberry Disease Info: Learn How To Treat A Sick Boysenberry Plant

By: Mary Ellen Ellis

Boysenberries are delightful to grow, giving you a harvest of juicy, sweet berries in the late summer. This cross between raspberry and blackberry varieties is not as common or popular as it once was, but it should be. You can grow this berry in your yard, but watch out for common diseases.

Diseases of Boysenberries

Boysenberry plants are susceptible to most of the same diseases as blackberries and dewberries. Know what the common boysenberry diseases are so you can watch for the signs and catch them early for management and treatment.

  • Cane and leaf rust. This fungal disease causes yellow pustules to develop on the leaves and canes of boysenberry plants. Over time, the canes and leaves will dry and crack.
  • Anthracnose. Another fungal infection, this one first manifests as small purple spots on leaves and new shoots. On canes, they will grow larger and turn gray. There may also be dieback.
  • Spur blight. The fungus that causes spur blight develops as purple blotches on canes. New shoots and buds will die back.
  • Orange rust. Small, yellow spots on leaves are the first signs of orange rust, a fungal disease. Eventually, they grow into pustules that produce orange spores.
  • Fruit rot. This occurs when the ripening fruit rots on the canes. Overripe berries are most susceptible.

How to Treat a Sick Boysenberry

Many common boysenberry problems can be easily managed in the home garden, especially if you are looking out for symptoms and catch them early or use preventative measures:

If you see the signs of cane and leaf rust, simply prune out the affected canes. Burn them to avoid spreading the infection. The infection should not greatly affect your harvest.

Anthracnose may cause die back, and there is no good treatment for it. A spray with fungicide in the late dormant period can help prevent it, though.

With spur blight, you can remove and burn the affected canes. Also consider using a copper fungicide in the bud stage to treat the infection.

Orange rust is a damaging and systemic infection. If allowed to spread too far, your plant will not produce any berries. Unfortunately, there is no fungicide that will treat orange rust, so you need to remove and destroy damaged plants, preferably before the pustules burst.

With fruit rot, prevention is best, although fungicide can be used to save berries that are starting to rot. Prevention includes spacing and pruning plants for air circulation and harvesting berries before they over-ripen.

Treatment and management is possible for most boysenberry problems, but prevention is always best. Use certified disease-free plants, provide plenty of space for air circulation, and make sure the soil drains well. When watering, apply water at the base of canes only, to avoid excessive moisture that can lead to disease.

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Read more about Boysenberries

Boysenberry facts and health benefits

Boysenberry Quick Facts
Name: Boysenberry
Scientific Name: Rubus ursinus
Origin Napa Valley region of California
Colors Color green changing to straw-yellow, amber, orangered, red, reddish black, to glossy purplish-black as they ripen.
Shapes 3 cm long and from 2 to 3 cm in width, an aggregate of numerous succulent drupelets, each containing a single seed.
Taste Sweet and little tangy taste
Calories 66 Kcal./cup
Major nutrients Manganese (31.39%)
Vitamin B9 (20.75%)
Total dietary Fiber (18.42%)
Iron (14.00%)
Carbohydrate (12.38%)
Health benefits Maintain a healthy blood pressure, Improve digestive health, Reduces the Risk of Kidney Stones, Prevents Diabetes, Healthier Vision, Takes Good Care Of Your Skin, Healthy Heart, Helps You Lose Weight, Increase bone strength, Healthy Brain, Helpful for pregnant women and their babies
More facts about Boysenberry

Boysenberry is a long trailing or climbing shrub, 6–7 m long. It is normally found growing in full sun to partial shade. It is usually grown on a support or trellis and needs to be protected from cold weather and strong winds. It thrives well in well drained, moist, loamy soil rich in organic matter. Leaves are normally imparinately compound with 3 shortly-stalked broadly ovate leaves with obtuse to acute to acuminate apices, serrated margins, adaxial surface darker green, abaxial surface pale green, pubescent or glabrous, with or without short prickles on the mid-vein and petioles. Similarly flowers are 2–3 cm across produce in short racemes or cymes on flori-canes with 5 reflexed sepals, 5 mostly white spreading petals, numerous short stamens and few to many carpels on an elongated receptacle.

The Boysenberry is a large bramble berry with many features that are direct reflections of its parentage. Its size, shape and color are similar to the blackberry, bold in size, oval shaped with onyx and ruby hues. Boysenberry is normally 3 cm long and from 2 to 3 cm in width, an aggregate of several succulent drupelets, each containing a single seed. Fruit is usually green when young changing to straw-yellow, amber, orangered, red, reddish black, to glossy purplish-black as they ripen. The fruit has soft, glossy, thin skin. They have rich, complex, and sweet flavor with just a hint of acid and are sweet and little tangy in taste. Normally fruit weights 8.0-gram (0.28 oz.). These berries are slightly tangy in taste and can be enjoyed fresh or made into pie fillings, jams, sauces, jellies and syrups. They will add a touch of sweet tartness to smoothies, dessert offerings and yogurt.

Boysenberry is named after by the originator, Rudolf Boysen, a Swedish immigrant and horticulturist who developed the crop during the Great Depression in the Napa Valley region of California. Boysenberry enjoyed commercial success under the growing guidance and development of farmer and berry “expert” Walter Knott of Knott’s Berry Farm. The Boysenberry’s popularity is the single most reason for making Knott’s Berry Farm so famous. Today, Boysenberry is grown as trailing vines throughout the Western Coast of the United States and they have been naturalized in Northern New Zealand, where the fruit is grown for commercial export. Over 60% of the world’s Boysenberry production comes from New Zealand. Boysenberry is also grown in Australia.

Nutritional Value

Apart from sweet and little tangy taste, boysenberry is a good source of nutrients, vitamins and minerals. Consuming 132 gram of boysenberry offers 0.722 mg of Manganese, 83 µg of Vitamin B9, 7 g of Total dietary Fiber, 1.12 mg of Iron,16.09 g of Carbohydrate, 0.106 mg of Copper,10.3 µg of Vitamin K, 1.15 mg of Vitamin E and 0.33 mg of Vitamin B5.

Boysenberry Problems - Information On Common Diseases Of Boysenberries - garden

Boysenberries are big, fat, delicious fruits that look like a cross between a raspberry and a blackberry – which in fact they are. They aren’t really a berry at all but they still taste good in spite of this mis-identification. Boysenberry plants behave just like blackberries and produce arching stems that can be as long as a car. In our gardens we generally restrain them by training them against a wall or fence or growing them into a tree or over a shed like a climbing rose. The berries are delicious raw or made into jam, high in antioxidants they are a ‘must’ if you have room for a plant or two.

Companions Marigolds to draw predatory insects like ladybugs and hoverflies

Quantity 1 plant per household – more if you have room.


  • Plants grow into large thorny bushes
  • May need support of trellis or frame
  • Varieties for all parts of country
  • Rich, acidic soil
  • Fat, juicy, delicious berries


There are over a hundred varieties of apple available in New Zealand. The best way to work out what suits you is to order catalogues from growers in late summer and match available varieties with your tastes, growing conditions and climate. Many apple trees are what’s called ‘self fertile’ meaning they can be grown on their own but some need another tree to help with pollination – this information is normally included on labels or in plant descriptions in catalogues. Take a look at some of the old-fashioned heirloom and heritage varieties that are returning in popularity, you’ll find some great apples not only rich in flavour but rich in history too.

Apples are divided into several categories and these may help you on your quest for what’s best:

Crab apple: old-fashioned varieties with small, bitter fruit that are most often made into jams, jellies and sauces. Often planted with other apple trees as a pollinator. ‘Floribunda’ is often planted for its delicate pink blossom and ‘Golden Hornet’ for its decorative profusion of red and yellow fruits.

Dessert apple: the common eating apple with sweet tasting juicy fruits – some of which are also good for cooking. Divides into three groups –
Early – Fruits start to ripen in early summer. Good varieties – ‘Oratia Beauty’, ‘Winesap’, ‘Devonshire Quarendon’.
Mid – Fruits ripen from late summer into autumn. Good varieties – ‘Freyburg’, ‘Golden Delicious’, ‘Egremont Russet’.
Late – Fruits ripen from mid autumn and are produced through winter. Good varieties – ‘Granny Smith’, ‘Braeburn’

Cooking apple: large fruits with thick skins and a tart bitter taste. Usually cooked and preserved. Trees often grow into large, spreading shapes and fruit ripens mid-to late season. Good varieties – ‘Bramley’s Seedling’, ‘Mayflower’ and ‘Sturmer’.

Getting started

The best time to plant boysenberries is from autumn into winter when plants are dormant.


Plant boysenberries in full sun. Good for growing countrywide, they can handle winter frosts down to -5 degrees centigrade. They are often trained against trellis or fences.

Boysenberries like a rich, free draining soil with lots of organic material in it. Soil should be slightly acidic – so look for lots of organic material as an indicator. If your soil is sandy or slightly sticky then you’ll need to add peat and well-rotted compost at the time of planting and continue to mulch with rich compost as your plants get established. You can always grow a boysenberry plant in a container or raised bed filled with peat and well-rotted organic compost if you have a sticky clay soil.



Plants should be spaced two strides apart. Soak plants in water before planting them.
Prepare the planting area. Soil should be weed-free and well dug through to at least a full spade’s depth. Add well-rotted compost and peat if necessary and mix with surrounding garden soil. Carefully remove boysenberry plant from container by turning it upside down and holding the plant across the base of its stem with a spread hand. Tap the bottom of the container until the plant and its root ball come loose. If it is in a plastic plant bag simply slit it down the side whilst the plant is standing in the planting hole, you can then slip the plastic bag from underneath. Handle plants by the root ball to prevent damage to stems and shallow roots. Place boysenberry plant in a hole that is just larger than the container it came in. Back fill around root ball making sure there are no air pockets. Water well and mulch with a finger-thick layer of peat, pine needles, shredded bark or untreated sawdust.
If planting in a container ensure it is large enough. Half barrels look good with boysenberries and they are the right size too. Use a rich compost with peat in it and plenty of organic material. Add slow release granules or sheep pellets before planting. When boysenberries are grown in containers they should be constantly monitored to ensure soil is moist – particularly in dry weather. Plants are often placed against a wall with trellis on it to which they can be attached or with a metal training pyramid or cylinder standing above the pot.


Keep plants weed free and maintain constant moisture levels – this is especially important during spring and summer when plants are growing and crucial once plants have formed fruit. Always water at the base of plants – avoid splashing foliage as this can spread fungal disease.

Feed: Depending on how well you have composted the ground you might want to give your developing plants an extra boost with some liquid seaweed or worm juice every 6 weeks. If you maintain a nutrient rich layer of mulch around their base this should give them all they need in the first few years as they become established.

Flowering: Boysenberries flower in spring, they are self-pollinated but bees will help to increase yields.

Care: Tie stems to training wires or trellis as they grow. Keep plants open and ensure good airflow – especially in warmer areas where humidity can result in fungal diseases like mildew.


Fruit are formed in spring and early summer when they start to ripen. Harvest does not last that long - normally between 4 and 6 weeks. Regular picking keeps fruit ripening. Fruits are ready when they turn from red to a deep, rich purple. They should come away from the stems easily when they are fully ripe. Taste is, of course, the ultimate test of readiness – boysenberries have a rich, sweet, rounded flavour. Don’t wash fruit as this causes them to deteriorate quickly. A mature plant can yield up to 4kg of fruit in a season.
Storage: Boysenberries keep in the fridge for up to a week as long as they are not piled high in a bowl. To freeze, pop freshly-picked, unwashed berries onto a plate or tray in the freezer. When they are frozen add them to a bag. Repeat this process over a period of time until you have frozen and stored all you want. When they are defrosted they will collapse due to excess moisture and are best used in puddings and jams where they are cooked.


In winter cut back all the canes that have produced fruit to ground level and remove any others that are damaged or spindly and weak. Fresh young canes left on the plant will grow to produce the next season’s crop, pinching out their tips encourages growth of fruit bearing side shoots.


Boysenberries can suffer from a range of pests and disease - some of which are easier to deal with than others. Green vegetable bugs, caterpillars and passion vine hoppers can be tricky customers to regulate in larger plants. Aphids, thrips and scale insects can be treated with Neem oil spray. If grown in the right soil and the right location and kept weed-free plants should be less susceptible to diseases such as mildew. Birds are an issue as soon as fruit start to ripen so protect your plants with mesh.

Nutrition Facts

Based on data from the NCC Food and Nutrient Database, the following tables show the nutritional values for boysenberries per 100-gram serving.

Nutrition Facts For Fresh Boysenberries (per 100g)
Calories/Nutrient Amount
Calories 43 kcal
Carbohydrate 9.61 g
Fiber 5.30 g
Sugar 4.31 g
Fat 0.49 g
Saturated Fat 0.01 g
Monounsaturated Fat 0.05 g
Polyunsaturated Fat 0.28 g
Omega-3 Fatty Acids 0.09 g
Omega-6 Fatty Acids 0.19 g
Protein 1.39 g
Vitamin Profile For Fresh Boysenberries (per 100g)
Vitamin Amount % DV
Vitamin C 21.0 mg 35.0 %
Vitamin K 19.8 mcg 24.8 %
Vitamin E 1.43 mg 7.1 %
Folate 25.0 mcg 6.3 %
Niacin (B3) 0.65 mg 3.2 %
Pantothenic acid (B5) 0.28 mg 2.8 %
Riboflavin (B2) 0.03 mg 1.5 %
Pyridoxine (B6) 0.03 mg 1.5 %
Thiamin (B1) 0.02 mg 1.3 %
Choline 8.50 mg 1.5 %
Vitamin A 10.7 mcg RAE 1.2 %
Mineral Profile For Fresh Boysenberries (per 100g)
Mineral Amount % DV
Manganese 0.65 mg 32.3 %
Copper 0.17 mg 8.3 %
Magnesium 20.0 mg 5.0 %
Potassium 162.0 mg 4.6 %
Zinc 0.53 mg 3.5 %
Iron 0.62 mg 3.4 %
Calcium 29.0 mg 2.9 %
Phosphorus 22.0 mg 2.2 %
Selenium 0.40 mcg 0.6 %
Sodium 1.0 mg not a problem for the vast majority of people, some individuals are sensitive to them.

For instance, an estimated 2.5% of people within the EU have salicylate intolerance (24).

The various symptoms of salicylate intolerance may include

  • Bronchial asthma
  • Rhinitis
  • Intestinal inflammation
  • Diarrhea
  • General intestinal/skin complaints

Boysenberries are not suitable for a low-salicylate diet.

As always with any medical concern, individuals who suspect they may have a salicylate intolerance should discuss this with their doctor.

2) Canned Boysenberries Are High In Sugar

The three most typical forms of boysenberries that we can buy are

  • Fresh
  • Frozen
  • Canned

The first two of these options are simply pure boysenberries with no additives. However, canned boysenberries contain large amounts of added sugar.

To illustrate this boysenberries canned in heavy syrup contain 22.3 grams of carbohydrate per 100 grams, most of which is added sugar (25).

In contrast, an equivalent amount of fresh berries contains only four grams of sugar.

Growing Boysenberries in Containers

Boysenberries can be grown easily in larger containers or flower pots.

For a single boysenberry plant, 18 inches wide and 12-14 inches deep flower pot is required.

After making several drainage holes, fill the container with good, slightly acidic potting soil, rich in organic matter and nutrients.

Plant the boysenberry seedling in the middle of the container and set several thin poles along the edge of the container - connected these poles with wire, effectively creating the cage where your boysenberry will grow.

Since the containers have limited volume, add fertilizers more often and water regularly - during hot summer days, water every or every other day.

In the smaller containers, keep number of canes limited - 5 to 7. In larger pots, for example 30 inches wide (

50 cm) deep, plant 2-3 boysenberry plants and keep total amount of canes to 10-15.

Note: when growing berries of this type in containers, gardener must be more 'aggressive' when pruning the plants .

Growing boysenberries in containers is highly recommended in colder areas and in smaller gardens. Don't forget, they are also very decorative plants.

Long Story Short - Boysenberries are excellent berries for small gardens. They are easy to grow, not very picky about the soil, water and nutrients, just be sure that they grow on sunny positions and prune them as required.

And when harvested, these berries are not kept well, so when harvested - eat them right away :)

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