Fruit and Foliage Diseases

Botrytis Fruit Rot; Gray Mold (Botrytis cinerea): Raspberries are very susceptible to fruit rots caused by fungi, especially during wet weather and heavy dews. To prevent fruit rots from becoming a major problem, encourage air circulation and rapid drying of the plants and fruit by maintaining narrow plant rows, and proper cane thinning. Harvest fruit regularly. Do not allow overripe or rotten fruit to remain on the plants.

Management: Infections can occur as early as bloom, so preventative fungicide sprays should be applied beginning at that time, and followed-up with additional sprays when wet weather is predicted. See pest management schedule for recommended materials and timing. To prevent molds from developing after harvest, cool the fruit as rapidly as possible after picking and maintain them at about 33˚F until they are sold. Never place raspberries in containers more than 3 fruit deep, and avoid rough handling.

Powdery Mildew (Sphaerotheca macularis): Powdery mildew affects susceptible cultivars of red, black, and purple raspberries. Blackberries and their hybrids are usually not affected. The disease can be severe (varying from year to year) on highly susceptible cultivars, and plants may become stunted and less productive. The fungus overwinters in dormant buds and in tips of canes. The infection of flower buds reduces fruit quantity, and infected fruit may be unmarketable as a result of the unsightly covering of the powdery mycelial growth.

Canby is highly susceptible to powdery mildew making it a poor choice for high tunnel production.

Infected leaves develop light green blotches on the upper surface. Generally, the lower surface of the leaf directly beneath these spots becomes covered by white, mycelial growth of the powdery mildew fungus. The leaf spots may appear water-soaked. Infected leaves are often mottled, and if surface growth of the fungus is sparse, they often appear to be infected by a mosaic virus. Infected shoot tips may also become covered with mycelial growth. When severely infected, the shoots become long and spindly (rat-tailed), with dwarfed leaves that are often curled upward at the margins. Infected fruit may also become covered with a white mycelial mat. When the disease is severe, the entire plant may be stunted.

Management: The easiest way to control powdery mildew is to promote good air circulation around canes. Removal of late-formed mildewed suckers in the fall may also delay the start of the disease build-up in the spring. See Pest Management Table for recommended fungicides and rates for controlling powdery mildew.

Late Leaf Rust (Pucciniastrum americanum): Late leaf rust, primarily a problem on fall bearing varieties, infects red, yellow and purple raspberries, but not black raspberries and blackberries. Symptoms appear as yellow masses of spores on the undersides of the foliage and on the fruit, making the fruit unmarketable. Unlike orange rust, late leaf rust is not systemic and can be eliminated from the planting.  White spruce and Englemann spruce serve as alternate hosts but once the disease is established in the planting, spruce are not needed for the rust fungus to survive.

Management: Plant disease free nursery stock.  Maintain good air circulation around the canes by keeping the rows narrow, thin out canes, maintain weed free rows and remove old canes from the planting to reduce overwintering inocculum. Fall bearing varieties Heritage, Caroline,  Jaclyn and Anne, as well as summer bearing Festival are highly susceptible. See Pest Management Table for recommended fungicides and rates for controlling late leaf rust.

Orange Rust (Arthuriomyces peckianus and Gymnoconia nitens): Orange rust can be caused by two stages of a single rust fungus, though different names are given to each stage. A. peckianus is the long-cycled state of the rust fungus that produces telia and teliospores and typically affects black raspberries. G. nitens is the short-cycled state of the rust fungus that does not produce teliospores and typically affects erect and trailing blackberries. Neither fungus has an alternate host, which is common for other rust diseases of raspberry.

Orange rust affects black raspberry and blackberry, but is not known to affect red raspberry. In early spring when new shoots begin growth, leaves appear stunted, misshapen, and orange spores can be observed on lower leaf surfaces. If conditions are appropriate, brown-black telia and teliospores will also form on the undersides of leaves. These spores will spread the disease to other plants. During late summer, the fungus moves into the plant's roots where it will overwinter. It overwinters on the plant in infected canes.The fungus infects systemically; once a plant is infected it will not recover. Infected plants will eventually become stunted with bushy growth and produce few fruit.

Management: Orange rust management begins by planting healthy and disease-free blackberry and black raspberry stock. Since wild blackberry and wild black raspberry plants can serve as a reservoir of the disease, remove and destroy these wild plants in the area. Promote good air circulation by keeping weeds down and using good thinning and pruning practices. Inspect plants in the spring for symptoms of the disease, and remove and destroy infected plants as soon as the first symptoms appear. A few chemicals are labeled for control of orange rust and are listed in the pest management table. However, fungicide controls are generally not considered effective for orange rust management.

Cane Diseases

Anthracnose (Elsinoe veneta): Anthracnose is a fungus disease which first appears as purple spots on the young canes. As the disease develops, the spots enlarge and become sunken. Small, white spots may appear on the leaves, and the fruit may develop brown, scabby areas. Individual drupelets become infected, sunken, and light tan in color; fruit has a bitter flavor. On older canes, the lesions will turn gray and cause the bark to split. Although this disease tends to be worse on black and purple raspberries, heavy infestations can cause serious yield losses in red raspberries. Anthracnose spores spread under wet conditions, so it is important to promote drying by ensuring good air circulation. This can be accomplished through careful pruning each year and removing all infected canes.

Management: This disease can be greatly inhibited by encouraging good air circulation, through maintaining narrow plant rows and good pruning and thinning practices. Immediately after harvest, remove all infected to ground level and destroy. Early spring sprays of lime sulfur on the canes will help prevent early infections. Lime sulfur should be applied before the emerging buds are 1/2” long, or plant damage will result. See pest management schedule for recommended materials and timing.

Spur Blight (Didymella applanata): Spur blight is a fungus disease which causes brown or purple blotches to appear on the canes, usually centered around a leaf stem. Symptoms appear on new canes in mid to late summer. On second-year canes, the blotches become gray areas on the bark with tiny black spots on them, which are the fruiting structures of the fungus. Leaves on infected canes may show yellow or brown areas which begin at the mid-vein and spread out to the leaf tip in the shape of a 'V'. Infected canes are weakened, and produce fewer fruiting branches than healthy canes.

Management: Similar to anthracnose, this disease can be greatly inhibited by encouraging good air circulation through maintaining narrow plant rows and good pruning and thinning practices. Red and purple raspberries are more susceptible than black raspberries, while blackberries are considered to be immune. Applications of lime sulfur to the canes in the early spring before the new buds are 1/2” long will prevent early infection. See pest management schedule for recommended materials and timing.

Cane Blight (Leptosphaeria coniothyrium): Cane blight is caused by a fungus and is characterized by large brown and purple lesions which form on the canes. Unlike spur blight, these lesions are not typically located at a leaf stem and may involve whole stems. Fruiting laterals exhibit weak growth and may wilt and turn brown. This disease is most common on black raspberries.

Management: To reduce the incidence of the disease, tip the canes when there is no chance of rain or heavy dew for 3 days, allowing the cut to dry. When pruning, remove old canes to the ground. Do not leave stubs. The fungus can overwinter on the old dead canes and continue to produce viable spores for many years. Control of cane blight is the same as for anthracnose or spur blight.

Root and Crown Diseases

Verticillium Wilt (Verticillium albo-atrum & Verticillium dahliae): Verticillium is a root rot fungus with infections favored by a cool wet spring causing the leaves on raspberry canes to yellow, wilt and fall off, progressing from the bottom of the cane to the top. These symptoms may only appear on one side of the plant and are most frequently observed during hot, dry periods. Young black raspberry canes may show a purple discoloration starting near the soil line and extending upward, while this is not as easily detected in red raspberry canes. Canes eventually die.

Management: Verticillium attacks a wide range of plants, including potatoes, tomatoes, peppers, eggplant and strawberries.It overwinters in the soil and on plant debris.  Do not plant raspberries following any of these crops. Non-host crops such as corn or wheat can help eliminate the fungus if grown for at least 2 years before planting raspberries. Many weed species, including pigweed and lamb’s quarters also carry the disease, so good weed control in the raspberry planting is essential. Preplant soil fumigation can help eliminate this fungus, but is quite costly. This disease is most serious on black raspberries.

Phytophthora Root Rot (Phytophthora spp.): The Phytophthora fungus invades the roots of raspberries and disrupts the vascular system, causing infected plants to produce weak, stunted canes, with small, off-color leaves. When dug up, the roots of these plants may look dead. Symptoms are most obvious in the spring, frequently causing this disease to be misdiagnosed as winter injury. In order to spread throughout a planting, the fungus requires flooded or saturated soils.

Management: Good soil drainage is critical for preventing this disease. The varieties Latham,  Newburgh, Prelude, Anne, Caroline and Killarney seem to have some resistance to Phytophthora, while Titan, Taylor, Festival and Hilton are very susceptible. Soil fungicide drenches in the spring and fall will provide control of Phytophthora, but should not be considered a substitute for good soil drainage and appropriate variety selection. This is only an emergency measure and it is better to move the planting to a more suitable location. See Pest Management Table for recommendations of specific materials and rates. Planting on raised beds helps with this problem and wet feet in general. Mulching new plantings with straw has been observed to increase the likelihood of Phytophthora infection the following spring, particularly in heavy soils.

Crown Gall (Agrobacterium tumefaciens) and Cane gall (Agrobacterium rubi): Crown gall is a widespread disease of all brambles caused by a bacterium. The bacteria enter the plant through wounds and induce galls or tumors on the roots, crowns, or canes of infected plants. Galls interfere with water and nutrient flow in the plants. Seriously infected plants may become weakened, stunted, and unproductive.

Young galls are rough, spongy, and wart-like. Galls can be formed each season and vary in size from a pinhead to several inches in diameter. They develop near the soil line or underground in the spring. Cane galls occur almost exclusively on fruiting canes and usually appear in late spring or early summer. Both crown and cane galls become hard, brown to black, woody knots as they age. Some disintegrate with time and others may remain for the life of the plant. The tops of infected plants may show no symptoms, but plants with numerous galls may be stunted, produce dry, poorly-developed berries, break easily and fall over, or show various deficiency symptoms due to impaired uptake and transport of nutrients and water. Infected plants may be more susceptible to winter injury.

Management: Control procedures include: (1) planting only nursery stock which is free of any obvious galls on crowns or roots; (2) not planting into a field where crown gall has occurred previously, unless a non-host crop, such as strawberries or most vegetables, is grown for two or more years before replanting; and (3) minimizing injury to root and crown systems during farm operations such as cultivation.

In addition to the above procedures, a nonpathogenic bacterium, Agrobacterium radiobacter, strain K-84, is commercially available for biological control of crown gall. The biocontrol agent may be applied to roots of healthy plants when they are first set out. After planting, the control becomes established in the soil around the root zone and prevents crown gall bacteria from entering this region. However, the biocontrol agent will not cure plants which are already infected before its application and is not labeled for use on bearing plants.

Viruses

Several types of viruses infect raspberry plants causing a variety of symptoms, including mosaic yellow patterning of the leaves, leaf curl and/or crinkle, cane dwarfing and crumbly berries. Once a plant becomes infected with a virus, it cannot be cured. All infected plants, including the roots, should be removed from the planting and destroyed. Viruses are typically spread by aphids, but in some cases (e.g., crumbly berry) nematodes may be responsible. When these creatures feed on infected plants they can take in the virus and then spread it to other plants. In order to prevent the spread of viruses, start with certified, virus-free planting stock. Plant your raspberries away from any wild brambles which may be harboring viruses that could be spread to your plants. A distance of at least 600 feet between cultivated raspberries and any wild brambles is recommended. Controlling the insects which spread these diseases is usually not a practical method of preventing infection. However, some raspberry varieties are resistant to aphid feeding and are thus somewhat protected. These varieties include Canby, Titan and Royalty.

Fruit and Foliage Insect Pests

Raspberry Fruitworm (Byturus unicolor): The raspberry fruitworm is a small (1/4”) brown beetle which feeds on the flower buds and leaves of raspberry plants during the spring and early summer. Female beetles lay eggs on the flowers and green fruit. The grubs that emerge are yellowish white, and feed on the fruit, attaining about 3/8” in length. Many of the flowers and fruit can be destroyed by this insect, and the larvae may end up in the harvested fruit, greatly reducing customer appeal.

Management: There is some evidence suggesting that this insect is more of a problem in weedy plantings. If early damage is noted, (e.g., small holes chewed in flower buds and skeletonizing of leaves), cover sprays should be applied prior to bloom. Adults (beetles) tend to be most active and noticeable on plants in the early evening hours. See pest management schedule for recommended materials and timing.

Tarnished Plant Bug (Lygus lineolaris): The tarnished plant bug (TPB) is a small (1/4”) bronze-colored insect with a triangular marking on its back. The immature stage, or nymph, is smaller and bright green, resembling an aphid, but much more active. Both adults and nymphs feed on the developing flowers and fruit, sucking out plant juices with straw-like mouthparts. This results in deformed fruit, with a few to many drupelets not enlarging, depending on the severity of the damage. Such fruit tend to crumble easily, and are generally unmarketable.

Management: Controlling weeds in and around the planting may reduce populations of this insect, but insecticide sprays may be necessary, applied prebloom and repeated after petal fall. If mowing around fields, do so after insecticides have been applied (to control migrating insects). Avoid planting alfalfa (which attracts high populations of TPB) near raspberries. White sticky traps are available for monitoring tarnished plant bug adults. These traps are used as an indication of when plant bugs begin their activity in the spring and a relative indication of their abundance, not as an indication of when to control this insect. Immature TPB (nymphs) are sampled by shaking flower trusses over a flat white surface. Thirty flower clusters should be sampled evenly from across the field (typically 6 clusters at 5 locations or 5 clusters at 6 locations). If 4 or more flower clusters are infested with nymphs (regardless of how many) a spray is recommended. A follow-up spray application may be made after bloom if TPB are still present in high numbers (check harvest interval before selecting material). See pest management schedule for recommended materials and timing. Do not apply insecticides during bloom.

Strawberry Bud Weevil (Anthonomus signatus): The strawberry bud weevil or “clipper” is an important pest of strawberries, but will also attack bramble fruit. This insect is a very small beetle (1/8”) with a copper-colored body and a black head with a long snout. The female weevil chews a small hole in unopened flower buds and lays an egg in the hole. She then girdles the stem just below the bud. The flower bud dries and dangles from the stem, eventually falling to the ground. The immature weevils, or grubs, develop in the girdled buds, emerging as adults in the early summer, and then migrating to wooded areas. These insects are not always present and may only cause minimal damage in raspberries.

Management: Examine the plants before bloom, and look for dead or clipped-off buds. Insecticides which are applied prebloom for control of raspberry fruitworm may also control this insect. See pest management schedule for recommended materials and timing.

Two-Spotted Spider Mites (Tetranychus urticae): Spider mites are very small (1/50”), insect-like creatures that feed on raspberry foliage, sucking out plant juices and causing a white stippling or bronzing of the leaves. Under heavy infestations, leaves will turn brown and be covered in a fine webbing. Adults may also move onto the fruit, reducing consumer appeal by their presence. There is currently little available for chemical control of this pest.

Management: Several companies commercially produce predatory mites which feed on spider mites. These predators can be released in raspberry plantings when mite populations are low, before the population gets out of control, and may provide some control of spider mites. It is important, however to encourage natural enemies of spider mites by reducing the use of pesticides which harm natural enemies. See source list at end of this guide for predatory mites. Spider mite outbreaks have also been associated with high levels of nitrogen fertilization.

Aphids: Aphids are small, pear-shaped, soft bodied insects which feed on plant sap with straw-like sucking mouthparts. Several species of aphids ranging from 1/16” to 1/8” in size, and dull yellow to bright green in color feed on raspberries. Most are wingless and slow moving. These insects tend to congregate on the underside of leaves, where their feeding causes the leaves to curl downward and be deformed. The most damaging aspect of aphid feeding is the spread of viruses. Aphids will take in a virus from infected plants, and later inject it into healthy plants. The virus then spreads throughout the plant, resulting in symptoms such as mosaic, leaf curl or stunting.

Management: To reduce the incidence of aphids and the transmission of viruses, start with certified virus-free plants; eliminate all wild brambles from within 600 feet of the planting; apply insecticides when aphids are first noticed in a planting; and rogue out all plants which exhibit virus symptoms. See pest management schedule for recommended materials and timing. The varieties Canby, Titan and Royalty are resistant to aphid feeding.

Japanese Beetles (Popillia japonica): Japanese beetles are about 1/2” long and copper-colored, with metallic green markings. They feed on raspberry foliage, skeletonizing the leaves during the mid and late summer. The larvae, or grubs, live in the soil, feeding on roots of grasses until late fall.

Management: The beetles can be controlled with insecticide sprays. However, pay close attention to days to harvest restrictions if fruit is present. Traps are available which use a sex and/or feeding attractant to capture the bugs in a can or plastic bag, but such traps generally do not provide adequate control. Place traps at least 100’ away from the planting. Traps placed within a planting may cause localized damage from beetles which are attracted to, but don’t fall into the trap.

Yellowjackets: Yellowjackets (aka hornets or wasps), are black and yellow stinging insects. They are closely related to the larger bald-faced hornets. Both groups of these insects are very aggressive and will sting with little provocation.

There are several species of these wasps found in the Northeast and, depending on the species, may build underground nests, large paper nests in trees or on houses. Many scavenge food, often dead insects or pieces of flesh from dead animals. Yellowjackets also have a great fondness for ripe fruit and can be found on pears, apples, raspberries, etc.

This fondness for fruit makes this insect a severe nuisance pest in raspberries, especially fall bearing varieties. They are a danger and annoyance to pickers. To help discourage the yellowjacket from feeding on raspberries, be sure to harvest berries as soon as they begin to ripen, even though there may be only a few early berries. Once the yellowjackets have discovered the berries, it is almost impossible to discourage them.

Management: Insecticide sprays for control of yellowjackets are not effective or recommended unless you know where a nest is and can eradicate it with a household hornet spray. This is best done in the evening when most of the members of the colony are in the nest. Yellowjackets can be discouraged by sanitation, which is regular and thorough, picking of all berries as soon as they begin to ripen, and frequent removal of overripe fruit and fruit debris.

There are many yellowjacket traps on the market, and various baits have been used with some success. Our (eastern) species of yellowjackets do not respond to trapping as well as western species. Different baits and traps may have to be tried to determine if any traps/baits will work in a particular raspberry planting. If traps are to be used, the key to success is to get the traps out early. Once yellowjackets have found the ripened fruit, the traps will probably not be of much help.

Potato Leafhopper (Empoasca fabae): Nymphs and adults are small (1/8”) green soft bodied insects. They move very quickly, often sideways, when disturbed. The potato leafhopper feeds on the underside of leaves leaving small chlorotic areas and causing a downward cupping of the leaves. Most feeding is on the upper, more succulent leaves on primocanes and often causes a stunting of those canes.

Management: This pest does not overwinter in New England but is brought up every year from the south on storm fronts. Insecticide applications may be needed when damage is observed. Plants recover quickly once these applications are made and normal growth resumes.

Brown marmorated stink bug (BMSB) (Halyomorpha halys): Adult BMSB are approximately 3/4 inch long and are shades of brown on both the upper and lower body surfaces. They are the typical “shield” shape of other stink bugs, almost as wide as they are long. To distinguish them from other stink bugs, look for lighter bands on the antennae and darker bands on the membranous, overlapping part at the rear of the front pair of wings; a black and white triangle shaped pattern along the edge of the abdomen; and rounded shoulder tips. Masses of 20-30 eggs are laid on underside of leaves. The 5 nymphal stages range in size from 1/8 - 1/2 inch. Nymphs and adult BMSB feed on many hosts including small fruits, tree fruits, vegetables, ornamentals, and seeded crops such as corn and soybeans. BMSB feeds by puncturing the fruit with piercing/sucking mouthparts, and injecting saliva which allows the insect to suck up the plant material through its mouthparts.

BMSB has become a serious insect pest throughout much of the mid-Atlantic states and southern New York. BMSB is known to be in all New England states and since 2014 has become an agricultural pest in southern New England.

Spotted wing Drosophila (SWD) (Drosophila suzukii): SWD are invasive vinegar flies (fruit flies) that can attack unripened fruit. Female SWD cut into intact fruit with their serrated ovipositor to lay eggs under the skin. This allows larvae of SWD to be present during ripening, leading to a risk of detection in ripe fruit after harvest. There is a greater risk of fruit contamination at harvest from SWD compared with native species that lay eggs only in already-damaged and rotting fruit. SWD seem to prefer brambles over all other hosts.

Management: Although flies are relatively easy to kill with insecticides, keeping berries free from infesation can be difficult because of near constant pressure of countless flies. Pest pressure is lower earlier in the season, during harvest of summer-bearing varieties, compared to very high pest pressure during harvest of fall-bearing varieties. To date, only frequent and repeated insecticide application throughout the ripening and harvest period have proven effective. Sprays would be recommended as a preventative measure on any fruit starting to ripen in the first weeks of August. Weekly coverage may be adequate under low pressure, but twice weekly sprays may become necessary for high pest pressures. Choose insecticides based on efficacy and preharvest interval and rotate between IRAC classes. Add 4-16 ox NuFilm P/100 gal with all materials to improve residual efficacy.

Cane Insect Pests

Cane Borers: Raspberries are attacked by two types of cane borers. The raspberry cane borer is a 1/2” long, slender black beetle with an orange band just below the head and has long antennae. The female beetles girdle the tips of young raspberry canes by chewing two rings, about a half inch apart, around the stems about 6" to 8” below the top. An egg is inserted into the cane between the two girdled rings. When the larvae, or grubs, emerge, they feed inside the cane, tunneling downward, and eventually destroying the cane. Soon after the cane tips are girdled, they wilt, blacken, and may fall off.

Management: As soon as the wilted tips are noticed, they should be cut off several inches below the lowest girdle mark. Remove the infested tips from the field and destroy them. Also eliminate any wild brambles near the field which may be harboring this pest.

The red necked cane borer is 1/4” long, slender, black with a “coppery” neck. Unlike the raspberry cane borer, it has short antennae. The red necked cane borer also causes a different sort of damage. The females insert an egg into young canes, usually within 10” of the base of the cane from late spring through mid-summer. They do not girdle the cane, but the presence of the egg, and later the grub, causes a swelling in the cane which can vary in length from 1/2” to nearly 3”. Larvae feeding within the canes weakens them and many may break off. Remove any canes showing swelling near the base.

Root and Crown Insect Pests

Raspberry Crown Borer (Pennisetia marginata): The adult phase of raspberry crown borer is an attractive clear-winged moth which resembles a wasp. These moths lay eggs on the underside of raspberry leaves in late July and August. When the eggs hatch, the young larvae crawl down the cane and into the soil to overwinter. The following spring, they bore into the base of the raspberry canes and feed on the plant tissue. This feeding interrupts the flow of water and nutrients to the cane, causing them to wilt and become weak and spindly. Early symptoms may include browning of the leaf margins on new canes. Eventually, the entire crown may die. Infected canes are easily pulled out of the ground.

Management: Elimination of all wild brambles in the area can reduce local populations of this pest.

Bramble Weed Management

The primary goal of weed management is to optimize yields by minimizing competition between the weeds and the crop. Weeds reduce yields by competing with the crop for water, space, light, and nutrients. Weeds also harbor insects and diseases and encourage vertebrate pests. Timely cultivation, wise use of herbicides, and never permitting weeds to go to seed are integral parts of a good weed management system. Many of the weeds found in crop fields are difficult-to-control perennial weeds that are not common in annual crop culture. New plantings usually have fewer perennial weed problems than older plantings. Annual and biennial weeds can also exist in these fields. Fields should be scouted at least twice a year (spring and fall) to determine specific weed problems. The selection of a weed management tool should be based on specific weeds present in each field. Several herbicides are labeled for use in this crop. A list of herbicides and their recommended uses is presented in Table 47.

Herbicides can be broadcasted or applied as a directed spray to the base of the crop. With a band treatment, only 1 to 2 feet on either side of the row is treated. The areas between the crop row are usually maintained with a mowed cover of sod, clover, weeds, or a combination of these. This cover is used primarily for erosion control and to improve trafficability in the field. With banding, less herbicide is needed in each acre. For example, a 3 foot band (1.5 feet on either side of the row) where rows are spaced 9 feet apart will require only one third the amount of herbicide normally required for a broadcast treatment.

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.

Cultivation and mulching are sometimes used as weed management tools. All cultivations should be timely and shallow to minimize crop root injury, to minimize loss of soil moisture, and to avoid repositioning new weed seeds to the soil surface. Mulches that are free of weed seeds and placed thickly enough can be very effective at reducing or eliminating most annual weeds from the crop row. They are seldom effective on perennial weeds. If mulches are used in combination with herbicides, use the lowest recommended herbicide rate to avoid crop injury.