Botrytis Dieback and Fruit Rot (Botrytis cinerea): This disease commonly affects many plants.  It can infect leaf and stem tissue but is most damaging when it infects flower and fruit tissue leading to fruit rot.  It overwinters in dead leaves and plant debris and on stems. Inoculum is produced from fruiting structures on canes, from dead leaves, and from mummified berries in the spring.

Management: To help minimize the disease, choose a planting site with good air movement and prune out weak canes to speed the drying of plants. Also eliminate weeds to aid in quicker drying of foliage and fruit and harvest fruit before it is overripe. Fungicides should be applied during bloom, with additional applications made during harvest, if necessary. See the following Pest Management Table for specific recommendations and rates.

Powdery mildew (Podosphaera mors-uvae): This fungal disease overwinters on currant and gooseberry twigs.  In early summer, a whitish, powdery growth appears on the surface of leaves, shoots, and branch tips. Infected berries become cracked and may shatter. Infected leaves may drop prematurely during hot weather. If left unchecked, the fungus can progress to the berries. Later in summer, the growth may turn from white to brown. Warm, humid conditions with poor air circulation favor powdery mildew. Prune and dispose of infected branch and shoot tips in early spring.  Severe infections can cause plants to become stunted and die. Some growers are experimenting with trellising gooseberries to improve disease management and harvestability. Certain horticultural oils (check labels) applied at first sign of mildew can prevent spread.

Management: Conditions of high humidity are most likely to lead to mildew problems.  Any cultural practices like pruning and plant spacing that can help improve air circulation and reduce humidity will reduce incidence of mildew infections. Sprays are most necessary during humid or wet weather in the spring. Apply when the first signs of powdery mildew are apparent and repeat as necessary. If oil is used, multiple applications may delay ripening or reduce sugar accumulation in the berries. The oil kills powdery mildew colonies on contact, thus, high water volumes and thorough coverage of the leaves and developing fruit are essential for good results. Many common pesticides (including sulfur) are phytotoxic when applied with or close to oil sprays; check label for specific restrictions. See the following Pest Management Table for specific recommendations and rates.

Anthracnose Leaf Spot and Septoria Leaf Spot (Drepanopeziza ribis and Mycosphaerella ribis): These diseases can both become serious problems, especially in wet, humid years. Symptoms range from brown spots and yellowing on leaves, young shoots, and stems to early defoliation. The fungi overwinter in infected dead leaf tissue.  Spores are released from this leaf debris in the spring and infect new leaf tissue. Small brown spots appear in early to mid-June and at this point both diseases are visually indistinguishable. Currant fruit may also become infected with Anthracnose. Severe infections cause berries to crack and drop. 

Management: These diseases can be suppressed by raking out and removing infected leaves after they have fallen and apply mulch to cover any inoculum that might remain.  Prune and trellis to improve air circulation and promote leaf drying. Overhead irrigation creates conditions especially favorable leaf spot development. Irrigate during morning hours to allow foliage to dry before the evening.  Fungicides applied before bloom, after petal fall and after harvest are also recommended. See the following Pest Management Table for specific recommendations and rates.

White Pine Blister Rust (Cronartium ribicola): This disease is the primary reason for limited commercial production of Ribes in the North America.  It is a complex disease that requires two hosts, susceptible varieties of Ribes and 5-needled pines (e.g., Eastern White Pine).  Symptoms on Ribes consist of yellow to orange spots appearing on less susceptible plants first in the spring. Larger patches of orange 'rust' appear on the underside of the leaves later in the summer. Symptoms are usually not severe on Ribes (although severe infections can defoliate plants), but infections in white pines can lead to tree death.

Management: Black currants 'Ben Sarek', 'Consort, Crusader', 'Coronet' and 'Titania' are considered resistant. Titania is the most widely planted variety in New England (where it is permitted) and was considered immune to WPBR in the past.  That immunity may no longer be stable and so some states are revising their regulations as related to allowing this and other 'immune' varieties.  It is important to check with your local Extension Specialists to determine the most recent status of this disease. Gooseberries, red and white currants are generally less susceptible. Ribes species 'Red Lake', 'Jumbo Cherry' and 'White Currant' are known to be less susceptible than 'Red Jacket', 'Green Hansa', 'Poorman' and 'Pixwell'. Avoid planting in high-risk areas (check with your University Extension office for help determining the risk category of your site) or within 1 mile of pine trees stands. If Rally fungicide is used for powdery mildew or anthracnose, it should also control white pine blister rust. See the following Pest Management Table for specific recommendations and rates.

Currant Cane Blight or Botryosphaeria Canker (Botryosphaeria ribis): Initial symptoms appear as yellowing foliage and leaf wilting of young shoots during spring and summer. Affected shoots may resemble currant borer damage, but will have not borer larvae or exit holes. Once the cane is dead and no longer transporting nutrients, the fungus will make small (2mm in diameter) round black survival structures, stromata, which burst through the epidermis near tips of infected shoots. This disease causes canes to become extremely weak and consequently break off during high winds in the fall and subsequent winter. All currant varieties may be affected however gooseberries are not known to be affected. 

Management: Watch for the rapid blight of young shoots during early fruit development, and scout mature canes for the small black survival structures prior to budbreak. Prune out and burn infected canes in spring. There are differences in resistance among cultivars, but it is variety specific and not linked to color traits. 

San Jose Scale (Quadraspidiotus perniciosus): These insects occasionally infest currant and gooseberry plants. They feed by sucking valuable plant juices, and in severe cases they affect the fruit as well. Scale insects are easily seen on the dormant wood.

Management: Prune out and destroy infested canes before new growth begins in the spring. Certain dormant oils applications (check labels) can help reduce infestations. See following Pest Management Table for recommended materials and rates.

Currant Aphid (Cryptomyzus ribis): These tiny, soft-bodied insects feed under young leaves toward the shoot tips, causing affected leaves to curl downward, blister, and become reddish. In severe cases, leaves become excessively distorted and fall off and the fruit does not ripen properly.

Management: Monitor for leaf symptoms early in the season to identify infestations early.  Naturally occurring beneficials may keep populations in check over time.  Insecticidal soap and certain horticultural oils (check labels) can help control aphid infestations not controlled by natural predators. Early bud break insecticide applications can also be made. See following Pest Management Table for recommended materials and rates.

Brown Marmorated Stink Bug (Halyomorpha halys): Direct feeding on fruit by adults and all stages of nymphs can cause serious damage.  Adults are mottled brown, about 3⁄4 inch long, and nearly as wide with a shield shape. Adults can be differentiated from common brown stink bugs by alternating brown and white bands on their antennae and along the edges of their abdomens. Nymphs are smaller and, like adults, exhibit white bands on brown antennae. Their coloration varies with instar, but each has some yellow or red coloration, and their eyes are red. Eggs are yellowish green, oval, and laid in clusters that are attached side to side on leaf undersides.  Adults overwinter in protected locations and emerge in spring. They lay eggs from May through August. Nymphs progress through five instars.

Management: Monitor using traps recommended by your Extension Specialists. If found, Pyrethroids are the most effective chemical class. Nymphs should be targeted during pesticide applications as they cannot fly away; a direct hit of nymphs or adults is necessary for efficacy. Natural enemies are present, but they have a wide host range and thus currently provide insufficient control.

Fourlined Plant Bug (Poecilocapus lineatus): Nymphs and adults feed on leaves with piercing mouthparts and cause stippling of leaves. The spots may turn from yellow to brown or black. Most damage is seen on the youngest leaves. The feeding injury can be easily confused with leaf spot disease. The plant bugs overwinter as eggs which are inserted in the shoots. In Connecticut, egg hatch begins in mid-May. The nymphs are red to yellow with stripes on their wing pads. Adults are yellowish-green with four black stripes, about 1/4 inch long, and appear by early June. There is one generation per year.

Management: The eggs are relatively visible on the canes, usually near bud scales, during the dormant season. These can be pruned off and destroyed. Dormant oil may have some effect on overwintering eggs. Insecticides should be targeted at the nymphal stage. Once the plant bugs become adults they may be harder to kill; they also may have started laying eggs. Malathion, when used for other pests, is very effective on fourlined plant bug nymphs.

Currant Borer (Synanthedon tipuliformis): Adults are about 1/2 inch long, clear-winged, blue-black, wasp-like moths with yellow bands on their abdomen. Adults are active from approximately June 1 to mid-July in Connecticut. The females lay eggs in the stems, particularly around leaf axils. These eggs hatch during the summer and the larvae burrow into the currant and gooseberry canes; where they overwinter until the following spring. Some larvae may take 2 years to complete development. Infested canes put out sickly growth in the spring. Repeated infestations may cause the death of canes.

Management: To prevent the next generation of moths from emerging, remove and destroy infested canes before June 1. Proper pruning to remove old canes is the best control. Insecticides may help with control of adult moths if timed properly. Use pheromone traps to monitor for adult flight activity. Danitol is labeled for currant borer but may cause an increase in two-spotted spider mites due to effects on natural predators. PyGanic has a short residual and may need repeated applications. Bt products may have some effect on young larvae before they enter stems. See following Pest Management Table for recommended materials and rates.

Currant Stem Girdler (Janus integer): Sawfly lays eggs on shoot tips and girdles the tips, which eventually die and fall off. The larvae can bore into and feed within canes.

Management: Cut off affected tips in May or June about 3 to 4 inches below the girdle, or if left until later in the season, about 8 inches below the girdle. See following Pest Management Table for recommended materials and rates.

Imported Currant Worm (Nematus ribesii): The full-grown sawfly larva is 3 inches long; it is green with yellowish ends, has a black head, and is covered with black spots. Shortly after the leaves are out in the spring, the larvae feed first in colonies and later singly, voraciously stripping the plants of foliage. A second brood occurs in early summer, and a partial third brood may appear depending on the weather. If numerous, they can strip a bush of its foliage in a few days.

Management: Monitor for and remove leaves harboring eggs by hand. Watch for larvae starting just after bloom as the fruits start to enlarge. Cultural control involves being observant of growing conditions and keeping plants vigorous. Insecticide applications may be made as soon as larvae are found feeding on the leaves.  See following Pest Management Table for recommended materials and rates.

Gooseberry Fruitworm (Zophodia convolutella): This greenish caterpillar feeds in fruit causing it to color prematurely and fall off. The adult is a grayish moth with a wingspan of about an inch. Larvae are about 3⁄4 inch long with a brownish head and green body with dark stripes along the sides when fully grown.  Hollowed-out berries that change color prematurely and dry up or fall to the ground. Clusters of berries and part of the stem may be wrapped in a silken webbing.

Management: Hand-picking infested berries provides some control. An insecticide may be needed starting at early fruit development and again 10 days later. See following Pest Management Table for recommended materials and rates.

Spotted Wing Drosophila (Drosophila suzukii): This pest is similar in appearance to other vinegar flies or fruit flies. Most adult males have one large black spot near the tip of each wing.  Adult females lack wing spots, but they have a large sawlike ovipositor visible with magnification. Larvae are 2–3 millimeters long, white, and have no obvious head. These tiny white larvae can be found in otherwise marketable fruit. Tiny holes surrounded by sunken tissue may be found where oviposition wounds were made. Spotted wing drosophila is a new pest and while it will feed on Ribes, it is not known if Ribes fruit are preferred over other available fruit in a given location.

Management: Vinegar traps can be bought or made and are used to monitor for pest presence, but they are not a method of control. Traps containing vinegar should be hung in the crop as the fruit begins to color. Pruning and canopy management to create an open bush with light penetration to the base and good air circulation will make the planting less desirable for SWD and reduce their abundance during fruiting.  Clean, thorough and frequent harvest is also important for managing the damage from this pest.  Do not allow fruit to drop or stay on the ground beneath the bushes as this gives SWD a good place to feed, lay eggs and proliferate.  When spraying, a tight spray schedule with thorough coverage and rotating IRAC classes (to avoid resistance development) is important.  Pyrethroids and spinosads are effective on the adults; neonicotinoids and some other broad-spectrum materials are considered less effective.  No effective control for larvae is currently available. See following Pest Management Table for recommended materials and rates.

Japanese Beetle (Popillia japonica): Japanese beetles have an exceptionally large host range, feeding on the leaves of over 300 species of plants, including apples, grapes, blueberries, raspberries, roses and plums. These beetles are metallic green, while the wing covers are a shiny bronze. Five white patches of hair along each side of their body and two white patches on the tip of their abdomen helps confirm identification.  Adult beetles may become serious pests skeletonizing leaves and scaring berries. Adults overwinter as grubs deep in the soil.  The grubs consume feeder roots and may also girdle or clip off larger roots. In spring, they move near the soil surface, where they finish feeding and pupate. Pupae are first cream color and become light reddish-brown with age. Beetles emerge as adults in late June or early July and can fly a long distance to feed. Infested plants may not show any outward signs of injury until a period of drought stress, when the reduced root system cannot provide enough water to the plant. Damaged bushes show low vigor and reduced production. 

Management: Beetles are best controlled as adults. Physical removal is a viable option for small growers. Remove the beetles by hand and put them in soapy water. Hand picking is most effective as the beetles first arrive. The best time to handpick beetles is in the evening and early morning, when they are less active. Research has shown that Japanese beetle traps attract more beetles than they catch, and will typically cause more damage to plants in a garden. Adults are generally easy to control with foliar sprays, but timing is difficult since these are highly mobile insects that may suddenly appear in the field. Unfortunately, sampling for white grubs may damage the roots of bushes. Growers should check new sites for white grubs before establishing a field, and take actions against grubs before planting. Adults are generally easy to control with foliar sprays, but timing is difficult since these are highly mobile insects that may suddenly appear in the field. Insecticides can help manage adults especially when small to moderate numbers of Japanese beetles are present.  Several contact, residual insecticides are available. See following Pest Management Table for recommended materials and rates.

Slugs and Snails (various species): Slugs are soft-bodied mollusks that resemble snails without a shell. Slugs feed on leaves of all Ribes species. They are most active at night and during cool, wet weather. Populations are greatest when weather is damp and the planting is mulched. Translucent silver to whitish slime trails are visible on damages plants. During cold weather, snails and slugs hibernate in the topsoil. During hot, dry periods or when it is cold, snails seal themselves off with a parchment like membrane and often attach themselves to tree trunks, fences, or walls. Snails and slugs feed on a variety of living plants and on decaying plant matter. They chew irregular holes with smooth edges in leaves and flowers and can clip succulent plant parts. They also can chew fruit and young plant bark. Because they prefer succulent foliage or flowers, they primarily are pests of seedlings and herbaceous plants, but they also are serious pests of ripening fruits that are close to the ground. Look for the silvery mucous trails to confirm slugs or snails caused the damage and not earwigs, caterpillars, or other chewing insect.

Management: A good snail and slug management program relies on a combination of methods. The first step is to eliminate, as much as possible, all places where they can hide during the day. Handpicking can be very effective if done thoroughly on a regular basis. After the population has noticeably declined, a weekly handpicking can be sufficient.To draw out snails and slugs, water the infested plants in the late afternoon. After dark, search them out using a flashlight; pick them up placing in a plastic bag or a bucket with soapy water and dispose of them. Snail and slug traps are commercially available. Snails and slugs have many natural enemies including ground beetles, pathogens, snakes, toads, turtles, and birds, but most are rarely effective enough to provide satisfactory control. Snail and slug baits can be effective when used properly in conjunction with a cultural program incorporating the other methods discussed above. However, baits alone won’t effectively control snails or slugs. Baits are toxic to all snails and slugs, including the predatory decollate snail and native species. Several types of snail and slug bait products are available. The timing of any baiting is critical; baiting is less effective during very hot, very dry, or cold times of the year, because snails and slugs are less active during these periods. Irrigate before applying a bait to promote snail activity, and apply the bait in the late afternoon or evening.

Ribes Weed Management

Good weed control begins years before planting. Begin by identifying perennial weed problems in the field. Eliminate these weeds before planting.  Early to mid-fall applications of glyphosate products can be very effective.

A permanent sod such as hard fescue between the rows is effective in controlling weeds in established plantings. Within-row weeds can then be controlled with appropriate herbicides or landscape fabric.

Herbicides labeled for use in bearing and nonbearing currants and gooseberries are certain glyphosate products (Roundup, Touchdown, and others), Gramoxone SL 2.0, Rely, and Surflan AS. Devrinol 50DF and Scythe are labeled for use on bearing and nonbearing currants. Fusilade DX, Select Max, and Gallery 75DF are labeled for use only on nonbearing currants and gooseberries (plants that will not be harvested for at least one year). Other formulations with the same active ingredients may exist that are labeled for the same uses.

Glyphosate products and Gramoxone, Scythe and Rely are nonselective postemergence materials. Glyphosate products are translocated within and therefore kill the entire plant, even though only a portion of the plant may have come in contact with the herbicide. Fusilade and Select are selective postemergence materials that are also translocated in the plant, but are effective only on grasses. Gramoxone and Scythe are non-translocated contact herbicides, and kill only the portion of the plant with which they come in contact. Because of this feature, the roots of treated weeds survive, and control of perennial weeds is only temporary. Good coverage is a necessity, as untreated portions of the leaves and stems will continue to live. Rely is partially translocated. Gallery, Surflan, and Devrinol are preemergence materials, so they must be applied before weeds have germinated. Gallery is effective against annual broadleaves, while Suflan and Devrinol are effective against annual grasses and certain annual broadleaves.  Before use, always consult the herbicide labels for precautions, reentry intervals, and other restrictions.

Weeds can develop resistance to herbicides. The Weed Science Society of America (WSSA) developed a grouping system based on the mode of action of different herbicides. WSSA Group numbers can be used as a tool to choose herbicides in different mode of action groups so mixtures or rotations of active ingredients can be planned to better manage weeds and reduce the potential for resistant species.

Preharvest Intervals

Remember that weeds compete with each other, not just with crop plants. Therefore, controlling a particular weed or group of weeds may allow another weed species to take over, requiring adjustments to your control strategies.