Cabbage aphid — Brevicoryne brassicae Linnaeus

Cabbage aphids — features of existence and measures of control

Contents

The cabbage aphid belongs to the genus Brevicoryne. The name is derived from the Latin words brevi and coryne and which loosely translates as small pipes. In aphids, there are two small pipes called cornicles or siphunculi (tailpipe-like appendages) at the posterior end that can be seen if you look with a hand lens. The cornicles of the cabbage aphid are relatively shorter than those of other aphids with the exception of the turnip aphid Lipaphis erysimi (Kaltenbach). These short cornicles and the waxy coating found on cabbage aphids help differentiate cabbage aphids from other aphids that may attack the same host plant (Carter and Sorensen 2013, Opfer and McGrath 2013). Cabbage aphids cause significant yield losses to many crops of the family Brassicaceae, which includes the mustards and crucifers. It is important to have a comprehensive understanding of this pest and its associated control measures so that its spread and damage can be prevented.

Figure 1. Cabbage aphids, Brevicoryne brassicae Linnaeus, on cabbage. Photograph by Lyle Buss, University of Florida, Entomology and Nematology Department.

Distribution (Back to Top)

The cabbage aphid is native to Europe, but now has a worldwide distribution (Kessing and Mau 1991). Severe damage to various plants in the family Brassicaceae has been reported in many areas including Canada, The Netherlands, South Africa, India and China. The cabbage aphid is widely distributed throughout the U.S. and has been found to be more of a pest in the southern states (Carter and Sorensen 2013).

Identification (Back to Top)

The cabbage aphid is difficult to distinguish from the turnip aphid (Lipaphis erysimi (Kaltenbach)). The cabbage aphid is 2.0 to 2.5 mm long and covered with a grayish waxy covering, but the turnip aphid is 1.6 to 2.2 mm long and has no such covering (Carter and Sorensen 2013).

The cabbage aphid and green peach aphid (Myzus persicae (Sulzer)) can be confused when they are both found feeding on cabbage plants. However, they have distinguishing morphological characteristics. For instance, the cabbage aphid is waxy with short cornicles. On the other hand, the green peach aphid lacks a waxy covering, and has long cornicles (Opfer and McGrath 2013). Moreover, green peach aphids mainly attack cabbage before heading (after transplanting, the cabbage seedling starts producing leaves, and eventually the cabbage plant begins to produce a small, tight head at the center of the group of leaves) begins, but cabbage aphids may attack the crop at any stage (Elwakil and Mossler 2013).

Figure 2. Cabbage aphid, Brevicoryne brassicae Linnaeus, winged alate and nymphs on cabbage. Photograph by Lyle Buss, University of Florida, Entomology and Nematology Department.

Hosts (Back to Top)

The cabbage aphid has a host range restricted to plants in the family Brassicaceae (=Cruciferae), which include both cultivated and wild cruciferous crops (Gabrys et al. 1997).

Major economically important host crops where significant losses have been found include cauliflower (Brassica oleracea L. var. botrytis L.), brussels sprouts (Brassica oleracea L. var. gemmifera DC), broccoli (Brassica oleracea L. var. italica Plenck) cabbage (Brassica oleracea L.), oilseed rape (Brassica napus L.) and other members of the genus Brassica (e.g., Indian mustard (Brassica juncea L.), white mustard (Sinapis (= Brassica) alba L.), black mustard (Brassica nigra L.), toria (Brassica rapa L.). It also attacks Chinese broccoli, Chinese cabbage (Brassica rapa, subspecies pekinensis and chinensis), radish (Raphanus sativus L.) and kale (Brassica alboglabra L.H. Bailey) (Kessing and Mau 1991). Cabbage aphid is an especially big problem in broccoli and cabbage production (Opfer and McGrath 2013).

Life History (Back to Top)

Aphids can reproduce two ways. In warm climates (e.g., in Florida and Hawaii), females give birth to female nymphs without mating. In this case, an aphid colony consists of females only. This occurs during warmer periods in temperate climates as well. In temperate climates, however, the mode of reproduction changes during the autumn as temperatures begin to drop. In response to low temperature or decrease in photoperiod, males are also produced (Blackman and Eastop 1984). Mating takes place and females lay eggs. The egg stage is the overwintering stage of aphids. Generations are overlapping, with up to 15 generations during the crop season (Hines and Hutchison 2013). The total life cycle duration ranges between 16 to 50 days depending on temperature. The life cycle is shorter at higher temperatures (Kessing and Mau 1991).

Figure 3. A cabbage aphid, Brevicoryne brassicae Linnaeus, colony or cluster on a cabbage leaf. Photograph by Lyle Buss, University of Florida, Entomology and Nematology Department.

Eggs: In temperate climates, eggs overwinter in plant debris near the soil surface (Hines and Hutchison 2013). Eggs are not laid in warm climates; females produce female nymphs directly (Kessing and Mau 1991).

Nymphs: In instances where eggs are not produced, the female gives birth to nymphs. Nymphs differ from adults (including wingless adults, known as apterae) in having less developed caudae and siphunculi. The nymphal period varies from seven to ten days. Winged forms develop and start migrating to new host plants only when plant quality deteriorates or when a plant becomes overcrowded.

Adults: Aphids are soft-bodied and oval or pear shaped with a posterior pair of tubes called cornicles, which project backward. Aphids have piercing-sucking mouthparts. Adult cabbage aphids can take on two forms: winged and wingless (Herrick and Huntgate 1911). Wingless adults are 1/10 inches long, oval-shaped and appear grayish-green or grayish-white due to their waxy covering (Hines and Hutchison 2013, Natwick 2009, Opfer and McGrath 2013). On the upper abdominal surface, eight dark brown or black spots are located beneath the waxy coating. These spots increase in size toward the posterior end. Winged females are smaller and lack the waxy covering of wingless females (Natwick 2009). The wings are short with prominent veins. The head and thorax are dark brown to black with dark brown antennae. The winged aphids have a yellow abdomen with two dark spots on the dorsal anterior abdominal segments. These two spots merge into a dark band across the last abdominal segment (Kessing and Mau 1991).

Damage (Back to Top)

Aphids feed by sucking sap from their host plants. They produce a sugary waste product called honeydew, which is fed on by ants. In turn, the ants provide the aphids with protection from natural enemies. Continued feeding by aphids causes yellowing, wilting and stunting of plants (Opfer and McGrath 2013). Severely infested plants become covered with a mass of small sticky aphids (due to honeydew secretions), which can eventually lead to leaf death and decay (Griffin and Williamson 2012). Cabbage aphids feed on the underside of the leaves and on the center of the cabbage head (Hines and Hutchison 2013). They prefer feeding on young leaves and flowers and often go deep into the heads of Brussels sprouts and cabbage (Natwick 2009). Colonies of aphids are found on upper and lower leaf surfaces, in leaf folds, along the leafstalk, and near leaf axils.

Figure 4. Cabbage aphids, Brevicoryne brassicae, Linnaeus colony (or cluster) on a cabbage stem. Photograph by Lyle Buss, University of Florida, Entomology and Nematology Department.

The cabbage aphid is of agricultural concern because it is a vector of at least 20 viral pathogens that can cause diseases in crucifers and citrus. Both wingless (apterae) and winged (alate) forms are able to transmit viruses, but the wingless aphids demonstrate a higher rate of transmission (Toba 1962). The cabbage aphid’s mode of pathogen transmission is non-persistent: the aphid picks up the virus by feeding on infected plants and transfers the pathogen to healthy plants by probing with its mouthparts or feeding (Kessing and Mau 1991). Aphids cause major losses to broccoli by reducing yield, with real damage being contamination of harvested heads of broccoli (Natwick 2009, Opfer and McGrath 2013). In Oregon, contamination of some broccoli heads may lead to the rejection the entire harvest by quality assurance programs managed by broccoli processors (Opfer and McGrath 2013).

Management (Back to Top)

Aphids are serious pests under cool and dry conditions. Cultural and biological control strategies can help reduce aphid infestation and use of pesticides while still maintaining yield and quality of produce. For large scale (commercial) production, insecticide application should be considered when 2% of plants are infested with aphids. It is important to add a spreader-sticker (liquid detergent to break the surface tension of droplets) to the insecticides to increase surface contact with the waxy covering of the aphids’ bodies (Griffin and Williamson 2012). If one can delay pesticide application before head formation in cole crops, it can save expenses and help to conserve natural enemy populations (Natwick 2009). For small-scale vegetable growers (home growers), aphids can be repelled by planting crops with reflective mulch-covered beds and monitored by filling yellow pans with water, if aphids are found in great numbers in the water traps additional control measures may be necessary (Griffin and Williamson 2012).

Action threshold: Fields should be scouted every week for signs of aphids (Webb 2010). In Minnesota and Florida, there is no specific threshold level for aphids on cruciferous crops, but insecticides should only be used when aphid populations are high (>50/plant) on very young seedlings/transplants up to

7 leaf stage, or on plants close to harvest, as a contaminant or marketability precaution. Some aphid populations can be suppressed by conventional insecticides used to control Lepidopteran pests. Bacillus thuringiensis (Bt) products are not effective on aphids. However, when these products are used to control diamondback moth and imported cabbageworm (in early season), the beneficial insect complex is maintained and that usually keeps aphid population under check (Hines and Hutchison 2013, Webb 2010). In a broccoli field, you can get a sense of aphid density using the 10 by 10 method, which involves pulling 10 broccoli leaves at 10 different spots in the field, then counting the number of aphids on them. If more than 20% of leaves are infested with aphids, then an insecticide application is recommended (Opfer and McGrath 2013).

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Cultural control: The field should be plowed immediately after harvest to prevent the spread of aphids to other crops (Griffin and Williamson 2012). It is important to rid the field and surrounding areas of any alternate host plants like mustards or other cruciferous weeds (Natwick 2009). Destruction of plant debris at the end of the season can help kill overwintering aphid eggs in temperate climates (Hines and Hutchison 2013). Planting a nectar plant to attract beneficial insects could also be helpful e.g., sweet alyssum (Lobularia maritima (L.) Desv.) as tested in cabbage (Webb 2010). Crop rotation with non-host crops is also beneficial (Kessing and Mau 1991). Choice of cultivar could also reduce aphid populations and damage. For example, the cauliflower cultivar ‘Smilla’ could be a good choice because it affects adult reproductive parameters (Jahan et al. 2013). Avoid replanting on land where an aphid-infested crop has been recently removed. Plant spacing is not considered as an effective approach for cabbage aphid control in canola (Brassica napus L.) crops (Razaq et al. 2012).

Biological control: Parasites and predators are important for regulating aphid populations. The parasitic wasp Diaeretiella rapae (M’Intosh) (Hymenoptera: Aphidiidae) lays eggs within half-grown nymphs (preferring 2nd to 4th instars over 1st instar nymphs and adults) and mummifies them, forming a light brown, hard shell around the aphid. Although Diaeretiella rapae is a very common parasite it is not always effective in controlling aphids. When the wasp populations are large enough to control aphids, the aphid population has usually exceeded damage thresholds. Protecting habitat that will foster the population and survival of natural enemies can help reduce the need for pesticides (Natwick 2009). Syrphid fly maggots, lady beetle adults and larvae, and lacewing larvae (aphid lions) are common predators of aphids. Seed extract of the Chinaberry tree (Melia azedarach) (Baidoo and Adam 2012, Kibrom et al. 2012, Mekuaninte et al. 2011), leaf extract of peppermint (Mentha piperita), and seeds and leaf extract of flowering lantana (Lantana camara) (Baidoo and Adam 2012) have showed promising results against cabbage aphid (Mekuaninte et al. 2011).

Chemical control: Many insecticides are effective against aphids. Care must be taken that sprays thoroughly wet the plants, because of the waxy nature of the pest and crop. To achieve maximum control with minimum efforts, proper surfactant proportions in combination with well-adjusted spray equipment are important (Kessing and Mau 1991). Aphids have been managed using insecticidal soaps (e.g. Safer Soap). Application timing is very important to keep aphids under control while conserving populations of natural enemies (Griffin and Williamson 2012, Hines and Hutchison 2013). A study on insecticide resistance in cabbage aphid carried out in Pakistan reports that aphids developed resistance to chemicals including methomyl, emamectin benzoate, and pyrethroids (cypermethrin, lambdacyhalothrin, bifenthrin and deltamethrin) and neonicotinoids (imidacloprid, acetamiprid, and thiamethoxam). Their resistance level was also found to increase progressively in concurrence with regular use on vegetables (Ahmad and Akhtar 2013).

Selected References (Back to Top)

  • Ahmad M, Akhtar S. 2013. Development of insecticide resistance in field populations of Brevicoryne brassicae (Hemiptera: Aphididae) in Pakistan. Journal of Economic Entomology 106: 954-958.
  • Baidoo PK, Adam JI. 2012. The effects of extracts of Lantana camara (L.) and Azadirachta indica (A. Juss) on the population dynamics of Plutella xylostella, Brevicoryne brassicae and Hellula undalis on cabbage. Sustainable Agriculture Research 1: 229-234.
  • Beirne BP 1972. Pest insects of annual crop plants in Canada. IV. Hemiptera-Homoptera V. Orthoptera VI. Other groups. Memoirs of the Entomological Society of Canada 85. 73 pp.
  • Blackman RL, Eastop VF. 1984. Aphids on the world’s crops. An identification and information guide. John Wiley J.
  • Carter CC, Sorensen KA. 2013. Insect and related pests of vegetables. Cabbage and turnip aphid. Center for Integrated Pest Management. North Carolina State University, Raleigh, NC. (5 September 2019)
  • Elwakil WM, Mossler, M. 2013. Florida crop/pest management profile: Cabbage. Agronomy Department, Florida Cooperative Extension Service, IFAS, University of Florida, Gainesville, FL. (5 September 2019)
  • Gabrys BJ, Gadomski HJ, Klukowski Z, Pickett JA, Sobota GT, Wadhams LJ, Woodcock CM. 1997. Sex pheromone of cabbage aphid Brevicoryne brassicae: identification and field trapping of male aphids and parasitoids. Journal of Chemical Ecology 23: 1881-1890.
  • Griffin RP, Williamson J. 2012. Cabbage, Broccoli & Other Cole Crop Insect Pests. HGIC 2203, Home & Garden Information Center. Clemson Cooperative Extension. Clemson University, Clemson, SC. (5 September 2019)
  • Herrick GW, Hungate JW. 1911. The cabbage aphid. New York (Cornell) Agricultural Experiment Station Bulletin. 300: 715-746.
  • Hines RL, Hutchison WD. 2013. Cabbage aphids. VegEdge, vegetable IPM resource for the Midwest. University of Minnesota, Minneapolis, MN. (2 October 2013)
  • Jahan F, Abbasipour H, Askarianzade A, Hasanshahi G, Saeedizadeh A. 2013. Effect of eight cauliflower cultivars on biological parameters of the cabbage aphid, Brevicorynebrassicae (L.) (Hem: Aphididae) in laboratory conditions. Archives of Phytopathology and Plant Protection 46: 636-642.
  • Kessing JLM, Mau RFL. 1991. Cabbage aphid, Brevicoryne brassicae (Linnaeus). Crop Knowledge Master. Department of Entomology, Honolulu, Hawaii. (5 September 2019)
  • Kibrom G, Kebede K, Weldehaweria G, Dejen G. Mekonen S. Gebreegziabher E. Nagappan R. 2012. Field evaluation of aqueous extract of Melia azedarach Linn. seeds against cabbage aphid, Brevicorynebrassicae Linn. (Homoptera: Aphididae), and its predator Coccinella septempunctata Linn. (Coleoptera: Coccinellidae). Archives of Phytopathology and Plant Protection 45: 1273-1279.
  • Mekuaninte B, Yemataw A, Alemseged T, Nagappan R. 2011. Efficacy of Melia azadarach and Mentha piperata plant extracts against cabbage aphid, Brevicoryne brassicae (Homoptera: Aphididae). World Applied Science Journal 12: 2150-2154.
  • Moon MS. 1967. Phagostimulation of a monophagous aphid. Oikos 18: 96-101.
  • Natwick ET. 2009. Cole crops: Cabbage aphid. UC Pest Management Guidelines. University of California Agriculture & Natural Resources. (5 September 2019)
  • Opfer P, McGrath D. 2013. Oregon vegetables, cabbage aphid and green peach aphid. Department of Horticulture. Oregon State University, Corvallis, OR. (2 October 2013)
  • Palmer, MA. 1952. Aphids of the Rocky Mountain region. Thomas Say Foundation, Vol. 5. 452 pp.
  • Razaq M, Maqsood S, Aslam M, Shad SA, Afzal M. 2012. Effect of plant spacing on aphid population, yield components and oil contents of late sown canola, Brassica napus L. (Brassicaceae). Pakistan Journal of Zoology 44: 991-995.
  • Toba HH. 1962. Studies on the host range of watermelon mosaic virus in Hawaii. Plant Disease 46: 409-410.
  • Webb SE. 2010. Insect management for crucifers (cole crops) (broccoli, cabbage, cauliflower, collards, kale, mustard, radishes, turnips) ENY-464. Entomology and Nematology Department, Florida Cooperative Extension Service, IFAS, University of Florida, Gainesville, FL. (5 September 2019)

Acknowledgements: Special thanks to Morgan Conn, Dr. Susan Webb, Dr. John Capinera and Dr. Howard Frank for their review of this document.

Authors: Harsimran Kaur Gill, Harsh Garg and Jennifer L. Gillett-Kaufman, Entomology and Nematology Department, University of Florida
Photographs: Lyle J. Buss, Entomology and Nematology Department, University of Florida
Web Design: Don Wasik, Jane Medley
Publication Number: EENY-577
Publication Date: October 2013. Latest review: September 2019.

An Equal Opportunity Institution
Featured Creatures Editor and Coordinator: Jennifer L. Gillett-Kaufman, University of Florida

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Aphids

Cowpea aphid colony on faba bean

© M. Miles, Queensland Government

Winged cotton aphid with nymphs on cotton leaf

© T. Grundy, Queensland Government

A wide range of aphid species can affect field crops. Most are small, with oval-shaped green, brown or black bodies. They often form colonies.

Description

Aphid species found in cereal crops include:

  • Diuraphis noxia —Russian wheat aphid
  • Metopolophium dirhodum— rose-grain aphid
  • Rhopalosiphum maidis— corn aphid
  • Rhopalosiphum padi— oat aphid, wheat aphid
  • Rhopalosiphum rufiabdominalis— rice root aphid.

Aphid species found in broadleaf field crops include:

  • Acyrthosiphon kondoi —bluegreen aphid
  • Acyrthosiphon pisum— pea aphid
  • Aphis craccivora— cowpea aphid
  • Aphis glycine— soybean aphid
  • Aphis gossypii— cotton aphid
  • Brevicoryne brassicae — cabbage aphid
  • Lipaphis erysimi— turnip aphid
  • Myzus persicae— green peach aphid
  • Therioaphis trifolii— spotted alfalfa aphid.

Damage

Rarely cause major damage in most crops. Aphids suck on sap, causing loss of vigour, and in some cases yellowing, stunting or distortion of plant parts. Honeydew (unused sap) secreted by the insects can cause sooty mould to develop on leaves. In crops such as cotton, the honeydew affects fibre quality. Aphids can also be vectors (carriers) for viruses.

Control

Control measures are usually not warranted, as a range of parasites and predators keep population numbers down. Exceptions may be where:

  • the crop is under moisture stress
  • heavy populations are observed
  • virus outbreaks are likely to be a problem.

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Chapter 3 — Aphids and Their Biocontrol

Abstract

Aphids are small, soft-bodied insects that are common pests of nearly all indoor and outdoor field crops, vegetables, fruit trees, and ornamental plants. There are different species of aphids, some of which attack only one host plant, while others attack numerous host plants. As well as causing direct damage by sucking sap and stunting growth and development, essentially reflecting yield parameters, they also act as potential vectors of plant viruses. The honeydew excreted by them occludes the stomatal openings of the leaves, hampering photosynthesis and respiration, and also favors the growth of black mold. Their prolific breeding, polyphagy, advanced degree of polymorphism, anholocyclic and/or holocyclic reproduction, parthenogenesis and telescopic generation, host alternation, and polyvoltinism make them a notorious pest.

Concerns about the risks that chemical pesticides pose to the environment and human health, as well as their increased costs, have increased the need for more research into nonchemical methods of crop protection. In nature, there are several organisms that feed, parasitize, or infect aphids causing heavy mortality. Among those that regulate their populations are their parasitoids and predators that are commonly used in biocontrol programs in greenhouses and fields. The majority of aphid parasitoids belong to the subfamily Aphidiinae (Hymenoptera: Braconidae) and a few species to Diptera. Aphid parasitoids have enormous potential that can be used in regulating the aphid population both in glasshouses and open fields. At present, a number of parasitic species are utilized in biocontrol of aphids. A dozen species are commercially propagated and traded throughout the world, more intensely in European countries and the United States. The constraints of biocontrol of aphids are multifold. The parasitoids are killed by their natural enemies (hyperparasitism and intraguild predation). The biggest obstacle to the use of parasitoids in aphid control is their mass propagation at an affordable cost. Unless natural enemies are made as readily available, biocontrol is likely to be a subject of academic interest with no practical role whatsoever. The potential for mass rearing of parasitoids is bright because new technologies are being developed to produce both aphids and parasitoids using artificial media. However, there is a need to consider the trade-off between producing and storing large quantities of parasitoids at low costs and the overall quality of the individuals that are released in crops. Measuring the fitness of mass-produced individuals remains a challenge, and such a measure is likely to change depending on the attributes of the aphid species present and parasitoids that are released. Quantifying these parameters should increase the reliability of biocontrol programs and contribute to their acceptance by growers.

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17 Common Diseases of Leafy Vegetables: Photos, Prevention, and Treatment

Januaris is a part-time gardener and author of farming guides. He loves to write about crops, pest control, fish farming, and beekeeping.

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Diseases of leafy vegetables can cause devastating effects to your crop. They can completely kill your crop or significantly reduce its quality, which means that you can incur great losses if one of the diseases strikes your garden.

Just in case you didn’t know, leafy vegetables refer to crops such as collard greens, kale, cabbage, spinach, broccoli, rape, cauliflower, lettuce, celery, and turnip among others. They belong to the family Cruciferae.

There are several diseases that attack leafy vegetables, and they are majorly caused by fungi, bacteria, or viruses. If you grow greens or planning to grow them, here are the common diseases of leaf vegetables, their causes, prevention, control, and treatment. See clear vegetable disease photos in order to exactly diagnose the problem with your crop!

What Are the Common Diseases of Leafy Vegetables?

  1. Downy Mildew
  2. Alternaria Leaf Spot
  3. Frogeye Leaf Spot
  4. White Spot
  5. Powdery Mildew
  6. Anthracnose
  7. Wirestem
  8. Bottom Rot
  9. Damping-Off
  10. Blackleg
  11. White Rust
  12. Bacterial Soft Rot
  13. Yellows
  14. Clubroot
  15. Black Rot
  16. Mosaic
  17. Root Nematode

1. Downy Mildew — The Most Common Leaf Vegetable Disease

Downy mildew is a fungal disease caused by Peronospora parasitica. It causes white mold and faint yellow spots on the dorsal and ventral sides of the leaves respectively.

The fungus thrives in cold and wet conditions, so you can prevent it by avoiding these conditions in your garden. Some practices that can cause cold and wet conditions are excess watering and over-head irrigation.

You can control downy mildew by uprooting the infected crop and burning it, and you can treat it by using the fosetyl-al fungicide.

2. Alternaria Leaf Spot

Alternaria leaf spot is caused by fungus Alternaria brassicae. The leaves of the infected crop (especially kales) have black or brown circular spots. With time, the spots enlarge and concentric rings appear on them.

You can prevent this disease by planting certified seed or disease-free transplants. You can also prevent it by avoiding wet and warm conditions in your garden as the fungus is very active under these conditions. Cruciferae weeds harbor the fungus, so you should eradicate them from your garden.

The best way to control Alternaria leaf spot is to uproot and bury or burn the infected crop. You can also spray your crops with a suitable fungicide immediately after you see the symptoms.

3. Frogeye Leaf Spot

Brought about by fungus Cercospora brassicicola, Frogeye leaf spot causes pale green, gray, or white spots on the leaves. The spots are bordered by a brown ring and can take any shape.

You can prevent this disease by planting fungus-free seed or transplants. Another great way to prevent the fungus is to improve soil drainage and avoid excess moisture in the garden. In addition, you can prevent it by doing proper weeding and crop residue removal.

You can control frogeye leaf spot by practicing crop rotation. Some copper products and fungicides like Benomyl can treat and control the disease. Use these chemicals immediately after you see the symptoms.

4. White Spot

White spot is a leafy vegetable disease caused by fungus Pseudocercosporella capsellae. The crop infected by the fungi usually has brown or gray spots on the leaves. The leaves later turn yellow and fall off within a few days.

The fungus can survive on seeds, so you can prevent it by planting certified seed. You can also prevent the harmful microorganisms by avoiding cool and damp conditions in your garden.

The best way to control white spot is to eradicate the infected crop. The disease spreads fast, so you should remove the sick crop immediately after seeing the symptoms. The fungus can be killed by suitable fungicides and copper products, which means that you can these chemicals to treat your infected crops.

SOLUTION

White spot was a major problem in my garden until I discovered this copper fungicide. It amazes me on how it clears out the disease in less than a week.

Even when the crops are heavily infected, this organic farming-friendly fungicide does the job of killing the harmful micro-organisms, reviving your crops, keeping your garden free from fungus and increasing your yield!

And the best thing about it is that it can deal with other fungal diseases mentioned in this article, including the downy mildew and alternaria leaf spot.

I would recommend that you get it if you have the fungal menace in your garden!

5. Bacterial Soft Rot

Bacterial soft rot is caused by Erwinia carotovora, and it’s one of the most common cabbage and collard green diseases. It causes dark, mushy patches on the stems and leaf stalks.

You can prevent bacterial soft rot by avoiding water-splashing in your garden. Farm tools can introduce the bacterium to your garden, so you should disinfect your tools before using them in your garden.

The best way to control the spread of the bacteria is to uproot and destroy the infected crop. Concerning treatment, you can use a suitable bactericide to kill the harmful microorganism.

6. Powdery Mildew

Powdery Mildew is a fungal vegetable disease caused by Erysiphe polygoni. It causes white powdery mold on the upper surface of leaves.

The fungus survives in cool and dry conditions, so you can avoid these conditions in order to discourage the pathogen from developing in your garden.

Powdery mildew can be treated with sulfur, so you can use the chemical on your vegetables when you notice the disease symptoms. As for the control, you can eradicate the infected crops to stop the spread of the pathogen.

7. Anthracnose

Caused by fungus Colletotrichum higginisianum, Anthracnose affects leaves & stems of vegetables like turnips, and causes small, gray, or black spots on these parts.

The harmful microorganism survives in weeds, so you can prevent it by removing any unwanted plants from your garden. You can also prevent the fungus by keeping your garden at a lower moisture level.

The affected crops can spread Anthracnose to the healthy ones, so you need to remove the infected crops from your garden in order to control the spread of the disease. You can try suitable fungicides to kill the pathogen.

8. Wirestem

Wirestem is caused by fungus Rhizoctonia solani which lives in the soil. The disease is recognized by reddish-brown patches on stems of leafy vegetables. The stem rots and peels off with time, exposing a wire-like wood.

The infectious microorganism is favored by moist soils and rotten plant remains. This means that you can prevent the disease by keeping your soil at the optimum moisture. If you have plant remains in your garden, dispose them to prevent the microorganism further.

The best way to control wirestem is to disinfect your soil. You can also control the disease by discarding any infected seedlings. The pathogen can be killed by fungicides that contain pentachloronitobenzene.

9. Bottom Rot

Caused by fungus Rhizoctonia solani, Bottom rot makes the lower leaves of the infected vegetables to turn black and wilt. The pathogen can move to the roots, causing root rot.

You can prevent this disease by disinfecting soil and planting materials. The infectious microorganism survives in a very wet soil, so you can do away with excess moisture to prevent it in your garden.

Bottom rot can be controlled by crop rotation, so ensure you do not grow leafy vegetables repeatedly in the garden when it strikes. In the case of treatment, you can use fungicides like Terraclor to cure the sick crops.

10. Damping-Off

Damping-off is another leafy vegetable disease caused by Rhizoctonia solani. It is also caused by Fusarium spp or Pythium spp. The fungus causes decay and wilt in seeds and seedlings respectively. The infected seedlings have light brown stems.

The pathogen survives is cold and wet soils, so you need to keep the soil temperature and moisture at optimum levels to prevent the occurrence of this disease in your garden. You need also to use certified seeds.

You should immediately disinfect your soil if you notice any symptoms of the infection. You should also dispose any infected seeds or seedlings. In addition, you can use Terraclor or any other suitable fungicide to treat the infected crops.

11. Blackleg

Blackleg is brought about by Leptosphaeria maculans which is a fungus that causes small, light brown spots on the stems. The spots are usually sunken and can enlarge, making the stem to deteriorate.

You can prevent the fungus by using certified disease-free seed. The microorganism is active in a wet soil, so you can prevent it by avoiding wetness in your garden.

You can use fungicides such as Thiram and Captan to treat vegetables infected by blackleg. If the infected crops do not respond to the treatment, uproot and burn or bury them in a dry soil.

12. White Rust

Caused by Albugo candida. White rust is a fungal disease recognized by yellow-white spots on the leaves and sometimes on the stems of greens.

You can prevent Albugo by disposing crop refuse before planting your crop. You should not allow cruciferous weeds to grow in your garden as they harbor the infectious microorganism.

The best way to control white rust is to practice crop rotation. This cultivation method prevents the buildup of the pathogen with seasons. Concerning treatment, you can try any suitable fungicide to kill the microorganisms.

13. Yellows

Yellows is a fungal disease caused by Fusarium oxysporum con-glutinans, and triggers formation of large, dull yellowish green patches on the leaves of vegetables.

The harmful microorganism survives in warm conditions, which means that you can prevent it by keeping your garden at lower temperatures. The disease can be spread by farm tools, so ensure you clean and disinfect your tools before using them in your garden.

The best way to control yellows is to plant certified seed or disease-free seedlings. You can try to kill the pathogen with fungicides such as Terraclor, Captan, and Thiram.

14. Clubroot

Clubroot is brought about by fungus Plasmodiophora brassicae, and causes leaves of the infected vegetable crop to turn yellow or pale green. The pathogen spreads to the stem and roots, causing club-like swellings on them.

You can prevent this disease by planting pathogen-free seedlings. The infectious microorganisms can be introduced to your garden by infested irrigation water and soil, so ensure your irrigation water is clean and your farm tools do not have soil particles from other gardens.

The plant sickness can be eliminated by fungicides such as Terraclor, so you can try them if your vegetables are infected. Concerning control, you can minimize the spread of clubroot by removing weeds that harbor it.

15. Black Rot

Black rot is caused by both fungi and bacteria (Xanthromonas campestris). It brings about yellow patches on the leaves of the infected crop. With time, the patches turn brown. The pathogen spreads to the veins and midribs of leaves and the stem, making them black.

The harmful microorganism can be introduced to your garden by contaminated equipment, irrigation water or plant materials. You can therefore prevent it by ensuring that anything you bring to your garden is disease-free.

You can control black rot by removing any infected crop from your garden. You can also practice crop rotation to prevent the buildup of the disease with seasons.

SOLUTION

When it comes to bacterial leafy vegetable diseases, there is only one organic bactericide that treats and cures the crops effectively. This is the most trusted bactericide for all bacterial diseases that affect not only leafy vegetables, but also other garden crops and plants.

See also:  Arachnida (Spiders, Scorpions, Mites, and Ticks)

In my garden, I have had only one incidence of bacterial infection, and it was dealt completely by this bactericide. Never to come back! It can treat fungus, but I would recommend that you leave that for the copper solution mentioned above.

If you think your garden has black rot, soft rot or any other bacterial disease, I would advise you not to hesitate to buy this bactericide.

16. Mosaic

Mosaic is a viral disease caused by Turnip Mosaic, and it causes dark lines on the leaf veins of the infected crop. The leaves can become discolored with time.

The disease is transmitted by aphids, so you can prevent it by controlling the insects in your garden. Another way to prevent the virus is to keep your garden free from weeds.

The best way to control mosaic is to uproot and bury or burn the infected crops. Crop rotation can also help with the virus.

17. Root Nematode

This is a Meloidogyne incognita nematode that causes knots on the roots of vegetables. The infected crop becomes stunted and can wilt with time.

The nematodes thrive in a warm soil, so you can prevent them by keeping your soil at lower temperatures.

The infectious organisms can survive in the soil for many years. If you think your soil has these nematodes, you can fumigate it to control them. You can also control them by practicing crop rotation.

In Conclusion.

Leafy vegetable diseases are many, but these are the most common ones. You can easily prevent, control and treat them with the help of the information provided in this article. If there is a disease that you can’t control or treat, you can get assistance from a plant pathologist, botanist or agricultural extension officer.

Do You Grow Leafy Vegetables?

If Yes, Have You Ever Dealt with Any of These Diseases of Leafy Vegetables?

Questions & Answers

Is it safe to eat the vegetables with a disease?

It is not possible to suffer from a plant disease, so it is safe!

My kales have a disease that is affecting the leaves then extends to the stem and finally the stem rots. Which chemical should I apply?

Symptoms? You can always start with the Copper Fungicide mentioned in the article.

what are the effects of pests and diseases in the vegetable garden?

Increased growing cost, low yields, lose of income, etc

What virus is turning my lower tomato leaves brown and crispy before they fall off? I put straw down, but it was no help. As a result, I had to cut down three peach trees due to leaf curl as there was sap everywhere and the peaches were the size of grapes with maggots inside.

It could be the Curly Top, Mosaic virus, or as a result of uneven watering, high temperatures, or dry spells. If your watering and temperatures are okay, then it is likely a disease spread by aphids and other insects. See how to control the insects here: https://dengarden.com/gardening/pests-leafy-vegeta.

can a viral disease cause Bollworms?

No, Bollworms can’t be caused by a virus.

What causes my Lacinato kale to curl back from the center vein, then curl around a center point?

It is highly likely to be the Leaf Curl disease, which is usually caused by fungi. Pests like aphids can also cause curling, but if you can’t see the insects, then it is the disease. You can get the copper fungicide mentioned in the article to see if you can control the disease.

What diseases have the following symptoms: yellowing of leaves, purple leaves and the leaves get soft and fall?

These symptoms can also be caused by inadequate nutrients or environmental problems. For diseases, there are a number that cause yellow leaves and you can check them from the article, but purple leaves are usually due to lack of certain nutrients like phosphorus, potassium, etc.

Whiteflies have attacked my sponge gourd and also a virus has infected them. How can I protect my sponge gourd from viruses and whiteflies?

My spinach has black spots on it. What is this and how do I treat it?

It’s a fungal disease and you can treat it with copper fungicide.

Is it safe to eat alugbati with purple dots on its leaves?

Yeah, as long as the dots don’t affect their taste and you cook them properly.

What could cause curly leaves in okra and fluted pumpkin with an accompanying white powdery substance?

In addition to the diseases outlined in this article that cause curly leaves, some tiny pests like aphids also cause the problem. See other pests here — https://dengarden.com/gardening/pests-leafy-vegeta.

what are the green bumps on front and back of leaf lettuce (black Simpson) in clusters?

It could be downy mildew/edema, frogeye or yellows developing. You can use the copper fungicide mentioned in the article.

Why do my potato plant leaves turn yellow then brown?

There are a number of factors that cause this — ranging from lack of certain nutrients and environmental factors to poor crop practices and diseases. See diseases with this symptom from the article.

What disease turns my tomato’s leaves brown?

It could be the bacterial canker disease, and you can try the BioSafe Disease Control Concentrate Bactericide mentioned in the article.

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Comments

Januaris Saint Fores

9 months ago from Intercontinental

Attaching pictures is not supported in the comment section, so you can just describe the symptoms.

Dennis sisi

May I sent the picture of my kale so you may see the disease and help me?

julius mwansa

I found the presentation on most common leaf vegetables educative and informative.

Januaris Saint Fores

17 months ago from Intercontinental

It’s likely to be powdery mildew, so try to avoid splashing water on the leaves. You can also try the fungicide included in the article.

Muvela

My kale crop is developing soft leaves as if they havevbeen soakeed in hot water annd the upper side of the leaf turns white while the bottom side remains green and after some it dries up what could be the problem

Chavela

Don’t think it’s downy on leaf lettuce. The bumps are green and same as plant. When I cut them, the white juice exudes the same as cutting off leaves. I think it might be the leaves nature. I eat it anyway!

Thanks for your support; you surely do know viruses! I will bet some of the copper product I saw on here. Thanks!

Januaris Saint Fores

24 months ago from Intercontinental

Mixing your soil with fumigants (special pesticides). I don’t sell certified seeds but you can find them in agricultural stores near you. And as I said, you can’t eat lettuce or any other crop produce after treating with the fungicide. Alright, this platform doesn’t support photos, but I got your description.

Sherry F1

Thank You So Much!!

How do I fumigate the soil?

Do you sell the Certified Seeds?

Can you eat the lettuce after you treat it with Copper Fungicide?

I tried to attach a photo but couldn’t.

Sherry F1

Thank You So Much..

Do you sell Certified Seeds?

How do I fumigate the soil?

I tried to attach a picture but couldn’t.

Januaris Saint Fores

24 months ago from Intercontinental

The fungicide penetrates through the crops so give it at least a week. To control the disease, you need to fumigate the soil. Certified seeds only come being disease free, so they can’t help in resisting an existing disease. You can send the photo.

Sherry F1

Hi Januaris Saint! THANK YOU SO MUCH FOR YOUR ARTICLE AND KNOWLEDGE. I have tried for the past 2-3 years to find out what’s going with my lettuce/tomatoes crop. I have 5 raised beds. I plants lettuce, tomatoes and cucumbers every year. I have tried to rotate my crop but it’s hard since I only have the 5 beds. And for the 1st time by reading your article I think I know what the problem is. I think I have the Frogeye Leaf Spot in the tomatoes bed. But it is kinda yellow too. And White Spot in my lettuce bed. Yikes/HELP.

I ordered the Copper Fungicide like you suggested.

Here’s my ?? Is it safe to eat my lettuce and toms after using this product if I wash it real good? Since I am getting this year after year is this in my soil? What can I do about it? You mentioned purchasing Certified Seeds. Would that work if it’s in the soil? Can I send you a photo of the fungus on my leaves? Thank You So Much.

Joseph G.Mulbah

Let me utilized this media to officially express my Heartfield gratitude and appreciation for your courageous, delligence and energetic hard work for your brillent elucidation on diseases that affect vegetable crops and their prevention measure. I must applaud you and say congratulations. You are a good agricultural practitioner and laborious agriculturalist. Keep it up

Januaris Saint Fores

2 years ago from Intercontinental

It could be pests then! Big pests like rodents can break leaves, and of course, the broken leaves start to rot.

Din Baron

Thanks Jan Saint.

It doesn’t look like any of diseases described above. Just overnight, four to six top jung leafs, start to hang down like someone broke it and just below leafs start to rot and attract the flies and stinks badly.

Would like to attach the photos but doesn’t allow me on this comment window.

Januaris Saint Fores

2 years ago from Intercontinental

Photos of your sick crop can help identify the issue, but it is highly to be one of the fungal infections described in this article! Try the multipurpose fungicide described above. It could also be due to a watering issue or even a weather issue!

Din

Would like to know why is top of my kale plants starting to rot suddenly?

zafa love

this information has been helpful to run my vegetables

Januaris Saint Fores

4 years ago from Intercontinental

Thanks WiccaSage for your comment. Most crop diseases in humid areas are fungal. You can use this information to prevent, treat and control the disease.

Mackenzie Sage Wright

I’m not familiar with some of these; I live where it’s humid so usually when one plant comes down with a disease it spreads like the plague.

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