Problems With Cranberries: Common Fixing Cranberry Diseases And Pests

Problems With Cranberries: Common Fixing Cranberry Diseases And Pests

If you’re looking for an unusual addition to your garden this year, cranberries are where it’s at. But before you dive into the bog head first, make sure you read up on some of the most common problems that can affect this sweet tart of a crop.

Cranberry Plant Problems

There’s nothing that says fall quite like the unassuming cranberry. What nature neglected in size and grandeur, it made up for in intensity and sheer unforgettably flavored berries. Growing cranberries at home can be challenging, since they have very specific growing requirements, but if you’re willing to give it a go, it’s best to be armed with information about problems in cranberry vines so you’re prepared. Both cranberry pests and diseases can be devastating and difficult to manage, but we’ll get you started on the path to success.

Common Cranberry Pests and Disease

As with many food plants, the problems with cranberries run the gamut from easy to handle to nearly impossible to manage. Some cranberry diseases are also very limited in range, meaning that cranberry bogs in Wisconsin may experience a disease that is only problematic in that region. If you have trouble identifying the culprit, don’t hesitate to turn to your local university extension for a full workup on your cranberry plants. Here are some common things to watch for in most locations:

Leaf spot. Several leaf spot diseases occur in cranberry, with red leaf spot, black spot, Protoventuria leaf spot and cladosporium leaf spot among the most common. If spots are small and aren’t affecting new growth, you may be able to tolerate the spots and correct the conditions encouraging leaf spot after harvest.

Watering early in the day so the leaves dry completely, improving drainage to allow beds to dry, and reducing nitrogen fertilizer can go a long way to preventing future outbreaks. If leaf spots are recurrent or damage fruits, a fungicide applied at bud break and during shoot elongation will help.

Upright dieback. When your otherwise healthy cranberry shoots suddenly develop wilt or yellowing at the tips, then turn orange-brown and finally die, even though they’re among other perfectly healthy shoots, you may be experiencing upright dieback. Upright dieback gives a cranberry bog a sort of salt and pepper look, with just a few dead tips dispersed within healthy patches of growth.

The first thing to do is reduce stress on your vines as much as possible, whether this means changing your feeding pattern, watering more or less, or treating an insect infestation. If that’s not enough to help vines recover, fungicide can be applied before early bloom to help prevent the spread of the underlying fungal disease.

Fruit rots. There are over a dozen fruit-rotting fungi that affect cranberry, some attack leaves, flowers and fruit, and others are limited to fruit alone. You can reduce the chance of any one of these fungi taking hold by removing all trash from last season, including mummy berries, which can be sources of fungal spores.

Thin vines and try to not overfeed them to prevent tender overgrowth and lowering the overall humidity of your cranberry stand. Also, make sure to thin out any volunteers that might appear, since they tend to produce a lot of vegetation instead of fruit, adding to any humidity problem you might have.

Caterpillars. Caterpillars love cranberries as much as you do, so it’s important to keep your eyes peeled for moths that may be laying eggs in your cranberry stands. Cranberry fruitworm, cranberry tipworm, black-headed fireworm and others can be devastating to your plants and your fruit production, especially if you don’t notice them until they’ve really set in.

Most caterpillars can be treated with targeted insecticides like spinosad, but be sure to apply it in the evenings, after bees are back in their hives. Spinosad has a very short lifespan, however, and may need to be reapplied as new waves of caterpillars hatch.

Sap-sucking insects. A range of sap-sucking insects, like spider mites and scale, also feed heavily on cranberry. Spider mites are difficult to see with the naked eye, but you’ll know them by their tiny spider-like threads of silk; scale insects are equally difficult to detect, but because of their camouflage and not their size.

Either pest can be eradicated using insecticidal soap or neem oil, applied according to the manufacturer’s directions.

Cranberry Rootworm Beetle

Factsheet | HGIC 2014 | Updated: Feb 24, 2021 | Print | Download (PDF)

Cranberry rootworm beetle (Rhabdopterus picipes) feeding damage on camellia foliage results in C-shaped holes.
Jim Baker, North Carolina State University, Management

The Cranberry rootworm beetle (Rhabdopterus picipes) is one of several leaf-feeding beetles and weevils that consume the foliage of woody landscape plants in South Carolina. These nocturnal-feeding adult beetles are shiny, dark bronze-black, about 1/4-inch long, and 1/8-inch wide. These beetles are seldom noticed because they hide in the landscape mulch during daylight hours, and the foliar damage appears similar to that of hail damage. The adults feed on landscape plants for several weeks in the late spring and early summer. Their feeding results in curved, C-shaped, and elongated holes in leaves of azalea, rhododendron, camellia, blueberry, hollies, roses, redbud, oakleaf hydrangea, and other shrubs. After feeding, the female adults lay eggs on the soil. Upon hatching, young beetle larvae move into the soil to feed on the roots of the host plant. They feed throughout the summer until fall and then move deeper into the soil to over-winter. The larvae pupate within the soil during early spring, and the adults emerge in late spring to begin foliar feeding and repeat the one-year life cycle.

Cultural Controls: Keep landscape plants as healthy as possible to tolerate the damage. If there is inadequate rainfall, irrigate plants weekly during the growing season providing 1-inch of water per week.

Cranberry rootworm beetle (Rhabdopterus picipes) feeding on azalea foliage resulting in curved, elongate holes.
Chazz Hesselein, Alabama Cooperative Extension System,

A soil analysis test is recommended to determine which nutrients are needed in the soil to improve plant growth and to determine if lime is required. In the absence of a soil test, fertilize plants with slow-release tree and shrub fertilizer, such as a 12-6-6, in early spring and again 6 weeks later at a rate of 1 pound per 100 sq ft. However, in the coastal counties of Beaufort, Charleston, and Horry, there is typically sufficient phosphorus that naturally occurs in the soil. Therefore, in these areas, use a 15-0-15 fertilizer around the shrubs during the spring. For proper nutrient management in landscape beds, have the soil tested the following fall or winter.

Although mulch provides a hiding place for adult beetles, it is quite beneficial to landscape plants in conserving soil moisture, regulating soil temperature, and suppressing weeds. Apply a 3- to 4-inch deep layer of mulch around woody shrubs.

Chemical Controls: Once flowering is over, shrub foliage should be sprayed with spinosad (a natural insecticide), bifenthrin, cyhalothrin, cyfluthrin, or permethrin as soon as feeding damage is detected. These are contact insecticides to control the adults feeding on the foliage. Also, spray to saturate the mulch or leaf litter beneath the shrubs, as during the daytime, the beetles hide in the mulch near the plants. To protect pollinating insects, do not spray during bloom. See Table 1 for examples of products labeled for foliar pest control on shrubs.

Alternatively, control can be obtained with soil drenches using a product containing imidacloprid. This a systemic insecticide that is taken up at the base of the shrub and moves upward into foliage and flowers. It may take one week for imidacloprid to translocate throughout smaller shrubs or up to a few weeks for larger shrubs. It is always best to apply imidacloprid after flowering to reduce the risk to pollinating insects. Be sure the plants are well-watered the day before application (to enhance insecticide uptake), then drench the soil around the base of the shrubs with a solution of imidacloprid. The amount of product to use is determined by the height of the shrub in feet, so follow the label directions for mixing with water. Systemic insecticide products generally protect shrub foliage for a year and are best applied in the spring. Because soil-applied insecticides, which are drenched around the base of the shrubs, do not move further outward into the root system, they will not kill the grubs feeding on roots nearby. See Table 1 for examples of products containing imidacloprid.

Table 1. Insecticides to Control Cranberry Rootworm Beetle on Shrubs.

Insecticide Active Ingredient Examples of Common Insecticide Products Labeled for Use on Landscape Ornamentals
Bifenthrin Ferti-lome Broad Spectrum Insecticide Concentrate & RTS 1
Hi-Yield Bug Blaster Bifenthrin 2.4 Concentrate & RTS 1
Monterey Mite & Insect Control Concentrate
Ortho Outdoor Insect Killer Concentrate
Ortho BugClear Insect Killer for Lawns & Landscapes
Concentrate & RTS 1
Bifen I/T Concentrate
Talstar P Concentrate
Up-Star Gold Insecticide Concentrate
Imidacloprid Bayer Advanced Garden 12 Month Tree & Shrub Insect
Control Landscape Formula Concentrate
Bonide Annual Tree & Shrub Insect Control w/ Systemaxx
Ferti-lome Tree & Shrub Systemic Insect Drench
Martin’s Dominion Tree & Shrub Insecticide Drench
Monterey Once A Year Insect Control II
Cyfluthrin Bayer BioAdvanced 24 Hour Lawn Insect Killer RTS 1
Bayer BioAdvanced Complete Insect Killer for Soil & Turf I RTS 1
Bayer BioAdvanced Insect Killer for Lawns RTS 1
Cyhalothrin Spectracide Triazicide Insect Killer for Lawns & Landscapes Concentrate & RTS 1
Martin’s Cyonara Lawn & Garden Concentrate & RTS 1
Permethrin Bonide Eight Insect Control Vegetable Fruit & Flower Conc.
Bonide Total Pest Control – Outdoor Concentrate
Bonide Eight Yard & Garden Ready to Spray RTS 1
Hi-Yield Indoor/Outdoor Broad Use Insecticide
Hi-Yield Lawn Garden Pet & Livestock Insect Control Conc.
Southern Ag Permetrol Lawn & Garden Insecticide Conc.
Tiger Brand Super 10 Concentrate
Spinosad Bonide Captain Jack’s Deadbug Brew
Bonide Colorado Potato Beetle Beater Concentrate
Conserve SC Turf & Ornamental Concentrate
Ferti-lome Borer, Bagworm & Leafminer Spray Conc.
Monterey Garden Insect Spray Concentrate
Natural Guard Spinosad Bagworm, Tent Caterpillar & Chewing Insect Control Concentrate & RTS 1
Ortho Insect Killer Tree & Shrub Concentrate
Southern Ag Conserve Naturalyte Insect Control Conc.
1 RTS = Ready to Spray (a hose-end sprayer)

If this document didn’t answer your questions, please contact HGIC at [email protected] or 1-888-656-9988.


Joey Williamson, PhD, HGIC Horticulture Extension Agent, Clemson University

This information is supplied with the understanding that no discrimination is intended and no endorsement of brand names or registered trademarks by the Clemson University Cooperative Extension Service is implied, nor is any discrimination intended by the exclusion of products or manufacturers not named. All recommendations are for South Carolina conditions and may not apply to other areas. Use pesticides only according to the directions on the label. All recommendations for pesticide use are for South Carolina only and were legal at the time of publication, but the status of registration and use patterns are subject to change by action of state and federal regulatory agencies. Follow all directions, precautions and restrictions that are listed.

Common Problems In Cranberry Vines - Recognizing And Treating Cranberry Plant Problems - garden

A lot of problems can happen in the garden that can confuse the average gardener. From germination, wilting, light conditions, diseases, watering, pest and much more! Below is an explanation for some of the most common problems that gardeners and farmers face when planting vegetable seeds.

Identifying and Treating Diseases

Seeds Do Not Germinate

Learning Download: Germination

This is a tricky one. Most of the time it will be an environmental condition and not the seeds. Most professional seed companies will not send seed that has been professionally tested at 85% germination. If it is just one seed variety then it may be the seed but if you have trouble with more than one it is most likely an environmental control.

Replant and make sure soil drains well

Replant and protect seed. Relocate

Seedling Wilt and Die

Learning Download: Wilt

Seedlings can be very fragile. Keeping healthy growing conditions can be a challenge for people who work, have children or just don’t have time.

Keep soil moist but not dry or damp

Usually causes root rot and plant dies where stem meets the soil

Seedlings don’t need fertilizer the first month of growth. Use a soiless mixture to start seeds

Treat with organic insecticide

Spindly and Reaching Plants

Learning Download: Spindly Plants

This is one of the most common occurrences for beginning gardeners. Tomatoes, peppers, and other vegetable stems will get long and skinny as though they are reaching for more light.

Use grow lights or sunny location. Do not burn plants.

Slow watering. Improve drainage.

Thin plants out. Increase spacing.

Do not fertilize seedlings.

Slow Growth

Learning Download: Slow Growth

Slow growth of vegetables plants can be a number of factors. Sometimes it can just be the nature of the plant to grow slow, other times it may be transplant shock.

Most vegetables need full light. Move to new location.

Use row covers or cloths to protect from cold.

Identify insect doing damage and remove pest.

Yellow Leaves

Learning Download: Yellow Leaves

Yellow leaves is a common problem on tomatoes for gardeners. It will affect other vegetables and usually means the same thing.

Most vegetables need full light. Move to new location.

Poor Yields

Learning Download: Poor Yield

Poor yields can be attributed to several things that go wrong in the garden.

Temperature too hot or cold. Grow varieties that are right for your climate.

Test soil, fix as needed. Too much nitrogen

How to Control Viburnum Leaf Beetles

The best protection against viburnum leaf beetles is to plant resistant varieties of the viburnum plant. Just like there are some varietals that the beetles prefer to eat, so too are there ones that they typically steer clear of, allowing to you get the beauty of the shrub without the added hassle of having to worry about bugs. Luckily, beetle "resistant" varietals include some of the most popular landscape viburnums, like:

  • Doublefile viburnum (Viburnum plicatum)
  • Korean Spice viburnum (Viburnum carlesii)
  • Leatherleaf viburnum (Viburnum rhytidophyllum)

If you already have viburnum shrubs in your landscape, keep a close watch on them throughout the year for signs of an infestation. In the early spring (before the eggs hatch) this means carefully examining the small twigs from the previous year’s growth for any evidence of egg-laying holes and scars. Increasing temperatures can cause those holes to swell, allowing the "caps" to fall off and eggs or larva to emerge. If present on your plant, you will need to prune out and destroy all infested wood before the eggs have a chance to hatch.

As new leaves begin to open on your viburnum throughout the summer, continue to check both sides of the leaves for larvae and again prune and destroy any obviously infected plant parts. If necessary, chemical pesticides are most effective when applied while the larvae are young. Adult viburnum leaf beetles tend to fly away or drop to the ground when disturbed and are often not eradicated completely with spraying. For the most effective treatment of a severe infestation, check with your local Extension Service for recommended pesticides.

Watch the video: Guidelines for Diagnosing Plant Problems