Rapeseed treatments, most common diseases and pests of this technical plant, Nexles

Rapeseed treatments, most common diseases and pests of this technical plant

The rapeseed (Brassica rapa) is an annual herbaceous plant that is very important for the world economy. Its seeds contain 42-48 oil that is used either in the food industry or in the biofuel industry. The rapeseed crop has the following advantages: it reacts well to fertilizers, you can use the same machinery as for cereals, it can be sowed and harvested outside busy periods, it is a great predecessor crop and a good honey plant.

Its root is a pivoting one, but poorly branched. The stem is erect, around 1.2-2 m high. The base leaves have petioles, are lyrate, pinnate, and the middle and top leaves are lanceolate, sessile. The inflorescence is a raceme, the pollination is entomophilous. The fruit is a silique, a plant can grow up to 800 siliques. The vegetation period is 270-300 days.

Climate and soil requirements

It needs around 2100-2500 degrees Celsius during the vegetation period. The minimum germination temperature is 1-3 degrees Celsius. The rapeseed is very pretentious towards water. It grows well in areas where the annual rainfall is 450-650 mm. It prefers deep soils, permeable, middle textured, rich in humus and calcium.

Preventing pest plants

If the rapeseed plantation is infected by pest plants, it will not longer grow and it will not be ready for the winter period. Herbicides that can be used to fight pest plants of the rapeseed crop: Galera SL, Agil 100 EC (pentru samulastra) , Fusilade Forte EC, Leopard, Pantera 40 EC, Sultan.

Main diseases

White mold (Sclerotinia sclerotiorum)

The plants that have been affected by this disease will turn yellow and wilt. Light colored spots (white or pale yellow) can be observed on the inferior side. As time passes, the spots grow larger, turn brown and become covered by a white felt, that represents the fungus’ fruition. The sclerotia germinate and in time it causes ascoma. One sclerotium can produce one or more ascoma. The ascoma are cup, funnel or disk shaped. Their color varies, from cream to brown.

Prevention and control measures:

  • Avoid cultivating the rapeseed on low and moist parcels
  • Treating the seeds before sowing
  • Crop rotation
  • Ploughing at the needed depth (20-25-cm)
  • Chemical treatments using Acanto Plus, Amistar Xtra, Caramba Turbo, Orius 25 EW;

Downy mildew (Peronospora brassicae)

This is frequent for young plants. It is characterized by the emergence of yellow leaf spots, which gradually turn brown. On the inferior side of the leaves, there is a white-gray fluff, that represents the fungus’ fruition. Conidia are dichotomic branched and the conidia are ellipsoidal and colorless.

Prevention and control measures:

  • Destroying the affected plants
  • Correct agricultural techniques
  • Early sowing
  • Crop rotation
  • Preventing pest plants
  • Treating the seeds before sowing
  • Chemical treatments using Equation PRO, Dithane M 45, Apron XL;

Powdery mildew (Erysiphe cruciferatum)

The roots will thicken and will have bumps on their entire length. As the diseases progresses, the affected roots turn brown and rot. This disease can affect the plant in every vegetation stage. The plants that have been attacked during early vegetation stages, will remain small, their leaves will become colored and turn red. When this disease affects mature leaves, it colors the leaves in a blue-green shade.

Prevention and control measures:

  • Using resilient hybrids
  • Crop rotation
  • Avoid planting the rapeseed on low and moist parcels
  • Keeping a neutral soil pH

Clubroot (Plasmodiophara brassicae)

The roots will thicken and grow bumps on their entire length. As the disease progresses, the affected roots will turn brown, soften and rot. The disease can be encountered during every vegetation stage of the plants. Plants which have been affected since their early vegetation stages will remain small, the leaves will become colored and turn red. If mature plants are affected, their leaves will receive a blue-green shade.

Prevention and control measures:

  • Using resilient hybrids
  • Crop rotation
  • Avoid planting the rapeseed on low and moist parcels
  • Maintaining a neutral soil pH

Alternaria blight (Alternaria brassicae)

Small stains, dot-shaped or linear of a black color grown on the silique. The stains gradually extend and cover large surfaces. The siliques that have been heavily affected will no longer develop and will easily open up, leaving the seeds to be easily shaken off. A dark brown formation grows on the surface of the dots, and it is formed of the fungus’ conidia.

Prevention and control measures:

  • Avoid planting the rapeseed on low and moist parcels
  • Crop rotation
  • Ploughing at the correct depth (20-25-cm)
  • Chemical treatments using Acanto Plus, Amistar Xtra, Caramba Turbo, Orius 25 EW;

Main pests

Rape beetle (Meligethes aeneus)

It chews the flower buds on the exterior and on the interior in eats the stamina and pistil. The flower buds become dried and fall off and the least affected ones produce small siliques that have twisted tips. The female chews a small opening in the flower bud and lays 1-2 eggs on the stamina. You can sometimes find up to 15 eggs inside a flower bud, laid by different females.

Prevention and control measures:

  • Chemical treatments using Karate Zeon, Calypso, Biskaya, Fastac, Proteus;
  • Crop rotation;
  • Correct agricultural-technical techniques;
  • Gathering and destroying vegetal residues;

Red turnip beetle (Entomoscelis adonidis)

It irregularly chews the margins of the leaves, leaving only the veins sometimes. It can also attack the siliques and flower buds. This beetle can also attack the hearths and spontaneous cruciferous plants. The females lay around 800-900 eggs inside the hearths, at a 3-4-cm depth inside the soil.

Prevention and control measures:

  • Treating the seeds before sowing
  • Chemical treatments using Karate Zeon, Calypso, Biskaya, Fastac, Proteus;
  • Crop rotation
  • Correct agricultural-technical procedures
  • Gathering and destroying the vegetal residues

Turnip sawfly (Athalia rosae)

When this pest attacks the plants, their leaves are chewed and pierced on their inferior side. At first, the perforations are small in size and then these enlarge and become round or oval and with regular margins. Larvae of around 17-18 mm long can be found on the wounded plants. Their heads and legs are black and the rest of their bodies is gray.

Prevention and control measures:

  • Chemical treatments using Actara, Decis Mega, Nuprid, Mospilan, Kaiso Sorbie;
  • Crop rotation;
  • Correct agricultural-technical procedures;

Cabbage shoot weevil (Ceutorhynchus assimilis)

The adults chew small cavities in the stems, peduncles, and flower buds and the larvae eat the seeds. While growing a larva eats around 6-9 seeds. The females lay their eggs in the siliques that are under development. They chew a small hole in the silique’s wall and inside every hole they lay an egg. A female can lay around 35-50 eggs. This pest is present in all areas where the rapeseed is grown.

Prevention and control measures:

  • Chemical treatments using Biskaya, Calypso
  • Gathering and destroying the vegetal residues
  • Crop rotation
  • Correct agricultural-technical procedures

Cabbage stem flea beetle (Psylliodes chrysocephala)

The larvae chew the petioles of the inferior leaves and then make their way towards the tips of the sprouts. The galleries the larvae have chewed can be easily filled with water and can easily freeze during winter. These galleries also represent gateways for the phytopathogen agents.

Prevention and control measures:

  • Chemical treatments using Kaiso, Karate Zeon;
  • Crop rotation

Tropinota hirta (Epicometis hirta)

It eats the flower organs of the rapeseed, sometimes event he young leaves. The adults are 9-12 mm long, on a matte-black color, covered with a gray fluff. It has one generation per year and it spends the winter as an adult, inside the soil. The females lay the eggs 4-8 days after mating. The larvae are not harmful.

Prevention and control measures:

  • Chemical treatments using Biscaya, Calypso

Large white (Pieris brassicae)

The larvae are 40-50 mm long. During their first development stage they are yellow and when fully developed they are gray. They have yellow, longitudinal strips. The larvae that belong to the last generation attack the rapeseed leaves during autumn. The affected plants will no longer develop properly until the first days of winter.

Prevention and control measures:

  • Chemical treatments using Decis Mega, Fury.


Cabbage Pests

ENTFACT-300: Cabbage Pests | Download PDF

by Ric Bessin, Extension Specialist
University of Kentucky College of Agriculture

Cutworms, imported cabbageworm, cabbage looper, diamondback moth larvae, and cross-striped cabbage worm can be each cause substantial damage to cabbage. These pests can cause serious damage to young transplants as well as causing serious leaf feeding damage to older plants. Damage to the head or wrapper leaves often reduces marketability. Because many of these pests are much more difficult to control as large larvae, controls will always be most effective when directed toward small larvae. So early detection of economic infestations is critical to the management of these pests.

Cabbage Looper

Watch for cabbage loopers particularly on the undersides of leaves along leaf margins, but they can be found anywhere on the plant.

Figure 1. Cabbage looper arches its back when moving.

The larvae are light green in color with a pale white stripe along each side and two thin white stripes down the back. The body tapers toward the head.

There are three pairs of slender legs near the head and two pair of club-shaped prolegs toward the other end. When mature, the larvae reach 1-1/2 inches in length. The ridged, white, round eggs are usually laid singly on the underside of the outer leaves. The pupae are brown, about 3/4 inch long and wrapped in a delicate cocoon of white tangled threads. The adult moth is a mottled, grayish-brown moth with a 1-1/2 inch wing span and a small silvery spot resembling a sock in the middle of each front wing.

Because the larvae have no legs in the middle area of their body, this area arches when the insect moves. All larval stages of the insect move with this looping motion.

Figure 2. A cabbage looper’s body is narrow near its head.

Large larvae will often curl up and drop down to the base of the plant when the leaf is disturbed. As they grow, they move toward the center of the plant. They generally feed on areas between leaf veins.

When scouting, examine the undersides of the lower leaves for newly hatched larvae. Pull back loose wrapper leaves and examine around the base of the head for larger larvae. Evidence of frass (excrement) at the base of the head aids in the detection of larvae. Because larger loopers are more difficult to control, it is important to time applications for younger larvae. Pheromone traps are available to detect adult cabbage looper presence and initiate field sampling.

Diamondback Moth

Diamondback moth larvae, despite their small size, can be very destructive to cole crops. Eggs are laid singly or in small groups on the undersides of lower leaves. Eggs are small, yellowish-white and somewhat football-shaped.

Figure 3. Diamond back larvae feed partway through the leaf and have a forked tail.

Larvae are small, yellowish-green, spindle shaped, and have a forked tail. When mature, larvae are 5/16 inch in length.

The pupae are found in a gauze-like cocoon attached to leaves or stems of the cabbage plant. The moth has a small, slender, grayish-brown body with folded wings. The wings of the male form three yellow diamond-shaped spots where they meet.

Larvae feed on all plant parts, but prefer to feed around the bud of young plants. The young larvae mine between the upper and lower leaf surfaces. Look for young larvae emerging from small holes in the underside of the leaf. Older larvae create irregular shot holes while leaving the upper surface intact. Larvae often drop from the plant on silk threads as soon as the leaf is disturbed.

Monitoring should begin when the plants are young. During cupping, larvae that feed on leaves in the bud are difficult to find unless the outer leaves are pulled back. Bud leaves of pre-heading plants should be examined if feeding damage is present. Their feeding on the bud may cause malformation of the cabbage head.

Imported Cabbageworm

The bullet-shaped eggs have distinct ridges and are initially white when laid but turn dark yellow as they mature.

The larvae are velvety green with a narrow, light yellow stripe down the middle of the back and have four pairs of prolegs in addition to the three pairs of legs toward the head. When mature the larvae reach 1-1/4 inches in length.

The pupae is greenish-brown in color and attached to the undersides of cabbage leaves. The adult is a white butterfly about 1-3/4 inches long tinged with yellow on the undersides of the wings and black spots-on the front wing.

Figure 4. Imported cabbageworm often feeds on young leaves in the bud.

Imported cabbageworm cause similar damage as loopers, but feed closer to the center of the plant. Larvae are often concealed next to veins or the midrib on the underside of the leaves. Feeding is not restricted to between leaf veins. Large larvae can be particularly damaging to young plants and can cause significant yield reductions. Scouting for eggs and larvae should begin as soon as the white butterflies are seen flying about during the day. Eggs are laid singly and found anywhere on the plant.

Cross-Striped Cabbageworm

The larva is bluish-gray in color with numerous black stripes running cross wise on its back. Below the transverse stripes on each side is a black and yellow stripe along the length of the body.

Figure 5. Cross-striped cabbageworm lays eggs in groups, so the larvae may be numerous on a few plants and absent on others.

When mature the larvae reach 3/4 inch in length. The larvae drop to the soil to pupate in a tight cocoon just below the soil surface. The scale-like eggs are light yellow and laid in masses of 20 to 30 on the undersides of the leaves. The moth is yellowish-brown to brown with dark zigzag markings and has a wingspan of about 1 inch.

Because eggs are laid in clusters, individual plants scattered over a field may be infested with large numbers of cross-striped cabbageworms. Larvae feed on all tender parts of the plant, but prefer terminal buds. Young leaves and buds are often riddled with holes.

Beet Armyworm

The beet armyworm is a major pest in the southwestern and southern US and an occasional invader of vegetable crops in Kentucky.

Figure 6. This beet armyworm has an egg of a parasitic fly behind its head.

The beet armyworm is a light-green to black larva with four pairs of abdominal prolegs and a dark head. There are many fine, white wavy lines along the back and a broader stripe along each side. There is usually a distinctive dark spot on each side just above the second pair of true legs.

Females lay masses of up to 80 eggs underneath a covering of cottony-white scales, as many as 600 eggs over a 3 to 7-day period. These eggs hatch in 2 to 3 days and the larvae first feed together in a group near the egg cluster. As they grow, they gradually move away from the egg masses. Many small larvae die during this wandering stage but the behavior tends to spread out the infestation. Beet armyworm is quite mobile, one larvae may attack several plants in a row. Older larvae may feed on fruit as well as leaves. After they complete their feeding, the 1-1/4″ inch larvae pupate in the soil in a loose cocoon containing soil particles and leaf fragments. The life cycle takes about a month to complete in warm weather.

Beet armyworm feeding on young tender growth can be very damaging to small transplants. Often a fine webbing is produced by smaller larvae near these feeding sites. Older plants can become rapidly defoliated. Vegetable growers should pay particular attention to fall plantings of beans, tomatoes, crucifers, and other truck crops.

Timing of insecticide applications is very important. Once larvae are 1/2 inch or longer, they become very difficult to kill with insecticides. So treatment must be targeted against young larvae. Only with frequent field surveys can these pests be detected and controlled effectively.

Flea Beetles

Several species of flea beetles attack cole crops in Kentucky. They are very small brown to black beetles that may have some yellow markings on their wing covers. The eggs are laid at the base of the plants. The white, brown-headed larva has three pairs of legs and is about 1/4 long when mature. Flea beetles over winter as adults in plant debris in and around the field.

Figure 7. Flea beetles leave small round holes in leaves.

Flea beetles can cause serious damage to seedlings and small plants. Look for «shot-hole» damage on the leaves. Severe infestations may stunt or even kill young plants. These beetles will jump when disturbed. Larvae are found in the soil and attack roots, but it is the adult feeding that is usually the primary damage.


Early detection of cutworm infestations means that controls can be applied before serious stand reduction occurs. Cutworms are recognized by their smooth skin, greasy gray color and «C-shaped»; posture when disturbed. Eggs are laid by the night flying moths on grasses, weeds, and other host plants.

Figure 8. Black cutworm is a common pest.

Subterranean cutworms feed at night causing serious damage to stems and foliage of young plants, during the day they retreat to their underground burrows. Stalks of plants may be cut. The variegated cutworm climbs the plants to feed on foliage and the bud. It may be found feeding on the developing head after cupping. Cutworm infestations are sporadic and often associated with sections of the field that are weedy, have high amounts of organic residue, or poor drainage. Fields need to be prepared and weeds eliminated at least two weeks prior to planting to reduce cutworm damage.

Southern Cabbageworm

A close relative to the imported cabbageworm, southern cabbageworm is a late season pest that be a problem in some years. Controls for other cabbage caterpillars will be effective against this pest.

Figure 9. Southern cabbageworm is a sporadic fall pest.

Cabbage Aphids

Aphids of any of several species present either dead or alive in sufficient numbers to reduce the marketability of cabbage. The pale-green cabbage aphid looks like other aphids but with a grayish waxy coat similar to cigarette ash. These aphids infest the undersides of leaves and suck sap. Infested plants may show signs of curling, wrinkling, or cupping of the leaves. Some plants may be stunted and produce unmarketable heads.

Figure 10. Cabbage aphids can be common during cool weather.

Cabbage Maggots

Eggs are deposited at the base of plants or crevices in the soil. The white, legless maggots feed or burrow into the roots and stems of the plant. They are blunt at the rear and pointed toward the head. The brown pupal cases are hard and egg-shaped. The adult is a dark-gray fly with smoky-gray wings, black legs, and three stripes on its back. They over winter in the soil as pupae, when the soils warms in the spring, adults emerge, mate, then search for suitable host plants for egg laying.

Figure 11. Cabbage maggot can cause serious losses to seedlings.

These maggots may eat small roots or tunnel into larger roots or stems. Infested plants become riddled with winding tunnels. secondary organisms are often introduced and colonize these wounds. Damaged plants may look wilted, gray-blue or purplish, stunted, or wilt during the heat of the day. Crops planted early when the weather is cool and wet for long periods of time are potentially at greater risk to damaging infestations of cabbage maggots.

Harlequin Bug

Harlequin bug is a stink bug and feeds with piercing-sucking mouthparts. The result is light-colored, fan-shaped spots on leaves. This pest tolerates many of the insecticides used a-on cabbage and can be particularly difficult to manage with organic controls.

Figure 12. Harlequin bug is very difficult to manage in organic systems.


Successful control of cabbage pests, particularly the leaf feeding caterpillars, depends on proper pest identification, timing of applications and insecticide coverage. because the different species caterpillars may be susceptible to different insecticides, it is important to identify the species involved in an infestation.

Most of the eggs of the foliage feeding caterpillars are laid on the undersurfaces of the leaves and the larvae, until mature, tend to feed on the underside of the foliage or in the bud. Thus, obtaining adequate coverage of the plants with an insecticide is difficult. Insecticides should be sprayed in high volume solutions (80 to 120 gpa) at high pressure (150 to 250 psi) through hollow cone nozzles. Because of the leaf texture of these crops, addition of spreading and sticking agents should also be used to improve coverage.

CAUTION! Pesticide recommendations in this publication are registered for use in Kentucky, USA ONLY! The use of some products may not be legal in your state or country. Please check with your local county agent or regulatory official before using any pesticide mentioned in this publication.





Rapeseed, Brassica napus subspecies, napus, is a large winter or spring annual oil crop in the Brassica family and is also known as rape and oilseed rape, and for a specific group of cultivars, ‘canola’. Rapeseed is related to mustard, cabbage, broccoli, cauliflower and turnip. Rapeseed plants grow from three to five feet tall and have yellow flowers with four petals. Rapeseed has a deep taproot and a fibrous, near-surface root system.

Rapeseed is primarily grown for its oil. A big challenge of profitable rapeseed production is the limited use and markets for the meal remaining after oil processing.. In some areas, rapeseed, which contains more than 40 percent oil, becomes more profitable than soybeans, which contain 18 percent oil. Rapeseed is is also beneficial as a cover crop and for annual forage. It provides good soil cover over winter to prevent soil erosion, produces large amounts of biomass, suppresses weeds, and can improve soil tilth with its root system. Rapeseed can also be grazed by livestock during the fall growth period.

People are sometimes confused between the use of the terms “rapeseed” and “canola.” Rapeseed is the traditional name for the group of oilseed crops in the Brassicaceae family. It can be divided into two types — industrial rapeseed or canola. Visually, the seeds of the two types are identical. The distinguishing difference between the two types is their individual chemical or fatty acid profiles. Generally, “industrial rapeseed” refers to any rapeseed with a high content (at least 45 percent) of erucic acid in the oil. The name ‘Canola’ was registered in 1979 in Canada and refers to the edible oil crop that is characterized by low erucic acid (less than 2 percent) and low levels of glucosinolates. This profile will focus on industrial rapeseed.

Forage rape (Brassica napus L.)

Some cultivars of summer annual rape (Brassica napus L.) are used for grazing. They are especially useful for finishing lambs, flushing ewes, for dairy cows and pastured sows. Forage rape is ready to graze 80 to 90 days after planting.


Traditionally, industrial rapeseed is produced for birdseed and oil for industrial purposes. Industrial varieties of rapeseed are used for non-edible purposes such as lubricants, hydraulic fluids and plastics. High-erucic-acid rapeseed (HEAR) oil is especially useful where high heat stability is required. One of the primary markets for HEAR oils is erucamide. Erucamide has been used for decades by plastic film manufacturers for use in bread wrappers and garbage bags and is preferred over cheaper alternatives for its production properties.


In the United States, the harvested acreage of rapeseed decreased from 200,000 acres in 2008 to 10,500 acres in 2016. The crop totaled more than 19.3 million pounds in 2016, with a value of $4.8 million. The average yield was 1,840 pounds per acre in 2016.

Field production of rapeseed is the same as that for winter canola. Rapeseed grows well on a wide variety of well-drained soils, prefers a pH between 5.5 and 8.3 and is moderately tolerant of saline soils. Rapeseed has been grown in the Pacific Northwest for more than 40 years. It was also produced in the Southern U.S. during the late 1980s and early 1990s.

To date, seed meal remaining after oil production has limited uses. The glucosinolates in the meal limit its use in livestock feed rations due to the antinutritional and negative physiological effects.

On-farm Biodiesel Production

On-farm biodiesel production is possible from rapeseed or canola. Economists at the University of Tennessee found that production form canola was financially feasible, whereas production from rapeseed was not due to a lack of market for the byproduct seed meal. Oregon State University researchers found financial losses to produce biodiesel from canola/ rapeseed.


Management of rapeseed for industrial for oilseed production is the same as that required for canola and similar to that for winter small grains. Equipment needed include a tractor, drill or broadcast seeder, sprayer, combine harvester and wagons for transportation, similar to the needs for other small-seeded grain or oilseed crops. Spraying for weed management may be done on farm or by commercial applicators.

Fertilizer needs vary based on yield potential of a production site, including both soil and rainfall potential. Nitrogen requirements range from 100 to 150 lbs/A. Phosphorus (P2O5) and potassium (K2O,) fertility needs vary with soil test levels. P2O5 recommended rates range from 0 to 80 lbs/A. K2O recommended rates range from 0 to 140 lb/A. Sulfer is also important for profitable rapeseed and canola seed production, Recommended fertility rates range from 10 to 30 lbs/A.

The industry for industrial rapeseed is fairly mature. However, with increased emphasis on renewable resources and biodegradability, there is a possibility of an increased interest in raw materials such as high erucic oil rapeseed Industry experts recommend that rapeseed for the industrial oil market be grown under contract.

Harvesting rapeseed

Seed shattering at harvest is a potential problem, so rapeseed is commonly swathed when seed moisture is about 35%.


Rapeseed cost of production are the same as those for canola.

Production budgets for canola and rapeseed are available online for North Dakota, Pennsylvania, North Carolina, Maine, and Georgia.


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