Clubroot

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Clubroot on cauliflower Knolvoet bij bloemkool (Plasmodiophora brassicae on cauliflower).jpg
Clubroot on cauliflower

Clubroot is a common disease of cabbages, broccoli, cauliflower, Brussels sprouts, radishes, turnips, stocks, wallflowers and other plants of the family Brassicaceae (Cruciferae). [1] It is caused by Plasmodiophora brassicae , [2] which was once considered a slime mold but is now put in the group Phytomyxea. [3] It is the first phytomyxean for which the genome has been sequenced. [4] It has as many as thirteen races. Gall formation or distortion takes place on latent roots and gives the shape of a club or spindle. In the cabbage such attacks on the roots cause undeveloped heads or a failure to head at all, followed often by decline in vigor or by death. It is an important disease, affecting an estimated 10% of the total cultured area worldwide. [5]

Contents

Historical reports of clubroot date back to the 13th century in Europe. In the late 19th century, a severe epidemic of clubroot destroyed large proportions of the cabbage crop in St. Petersburg. The Russian scientist Mikhail Woronin eventually identified the cause of clubroot as a "plasmodiophorous organism" in 1875, and gave it the name Plasmodiophora brassicae.

In 18th, 19th and early 20th century Britain clubroot was sometimes called finger and toe, fingers and toes, anbury, or ambury, these last two also meaning a soft tumor on a horse.

The potential of cultural practices to reduce crop losses due to clubroot is limited, and chemical treatments to control the disease are either banned due to environmental regulations or are not cost effective. Breeding of resistant cultivars therefore is a promising alternative. [6] [7] [8]

In cabbages

Cabbage clubroot is a disease of Brassicaceae (mustard family or cabbage family) caused by the soil-borne Plasmodiophora brassicae . [9] The disease first appears scattered in fields, but in successive seasons it will infect the entire field, reducing the yield significantly and sometimes resulting in no yield at all. Symptoms appear as yellowing, wilting, stunting, and galls on the roots. It is transmitted by contaminated transplants, animals, surface water runoff, contaminated equipment, and irrigation water. [9] The pathogen can survive in a field for years as resting spores without a host present and will infect the next crop planted if it is a susceptible host. This pathogen prefers a wet climate and a pH around 5.7, so proper irrigation and the addition of compounds that raise the pH can be used to control this disease. [10] Other control methods include sanitation to prevent transmission, chemical control, and resistant varieties.

Hosts and symptoms

Cabbage clubroot affects cabbage, Chinese cabbage, and Brussels sprouts most severely, but it has a range of hosts that it affects less severely like kohlrabi, kale, cauliflower, collards, broccoli, rutabaga, sea kale, turnips, and radishes. [11]

Wilting and yellowing of plants in cabbage field. Club root of crucifers symptoms field.jpg
Wilting and yellowing of plants in cabbage field.
Galls on plant roots. Club root of crucifers symptoms.jpg
Galls on plant roots.

Developing plants may not show any symptoms but as the plants get older they will start to show symptoms of chlorosis or yellowing, wilting during hot days, and exhibit stunted growth. Below ground, the roots experience cell proliferation due to increased auxin or growth hormone production from the plant as well as the pathogen. [10] This causes the formation of galls that can grow big enough to restrict the xylem tissue inhibiting efficient water uptake by the plant. Galls appear like clubs or spindles on the roots. Eventually the roots will rot and the plant will die. [11]

Disease cycle

In the spring, resting spores in the soil germinate and produce zoospores. These zoospores swim through the moist soil and enter host plants through wounds or root hairs. A plasmodium is formed from the division of many amoeba-like cells. This plasmodium eventually divides and forms secondary zoospores that are once again released into the soil. The secondary infection by the zoospores can infect the first host or surrounding hosts. These secondary zoospores can be transmitted to other fields through farm machinery or water erosion. They form a secondary plasmodium that affects plant hormones to cause swelling in root cells. These cells eventually turn into galls or “clubs”. The secondary plasmodium forms the overwintering resting spores which get released into the soil as the “clubs” rot and disintegrate. These resting spores can live in the soil for up to 20 years while they wait for a root tip to come in close proximity for them to infect. [12]

Environment

Clubroot is a disease that prefers warmer temperatures and moist conditions. Ideal conditions for the proliferation of this disease would be a soil temperature between 20–24 °C and a pH less than 6.5; therefore, this disease tends to be prominent in lower fields where water tends to collect. [12]

Management

Clubroot is very hard to control. The primary step for management and long-term control is exclusion of the disease. Good sanitation practice is important with regard to the use of tools and machinery in order to prevent the introduction of the pathogen to a disease-free field. It is not uncommon for an inattentive farmer or gardener to unknowingly carry in the pathogen after being previously exposed to it at a different time. One should avoid purchasing infected transplants of cabbage so as to prohibit the infestation of P. brassicae. Soil type is also an important factor in the development and spread of cabbage clubroot; the use of sand will allow for the plants to grow in well-drained soil, thereby eliminating the possibility of the pathogen to proliferate in a hospitable environment. [9]

Although it is difficult to eradicate the pathogen once it is introduced to a field, there are several methods for its control. Keeping the soil at a slightly basic pH of 7.1–7.2 by the addition of agricultural lime as well as the integration of crop rotation will reduce the occurrence of cabbage clubroot in already infected fields. Fumigation using metam sodium in a field containing diseased cabbages is yet another way to decrease the buildup of the pathogen. [13] Control and management practices on already infected fields help to reduce the overall impact that P. brassicae has on a field of cabbage and other cruciferous plants, but it is extremely difficult to rid an individual plant of the disease once it is already infected.

Importance

Clubroot can be a reoccurring problem for years because it is easily spread from plant to plant. P. brassicae is able to infect 300 species of cruciferous plants, making this disease a recurring problem even with crop rotation. [14] This wide host range allows the pathogen to continue its infection cycle in the absence of cabbages. Additionally, cabbage clubroot may be a stubborn disease due to its ability to form a microbial cyst as an overwintering structure. [14] These cysts may last many years in the soil until it comes into contact with a suitable host, making it difficult to entirely avoid the introduction of the disease. Those growing cabbage need to be aware of the possibility of Plasmodiophora infestation by simply growing in particular fields that may have had cabbage clubroot previously.

Canola infestation in Alberta

In 2003 clubroot was identified in Alberta, Canada, as an outbreak in canola crops in the central area of the province mainly isolated to the Edmonton area. Clubroot is a soilborne disease caused by the biotrophic protist Plasmodiophora brassicae. The infection causes the formation of large galls on the roots which look like clubs. These formations impede nutrient and water uptake and can cause plant death, wiping out important money generating canola crops. Initially 12 commercial fields of canola were identified, but that number grew to over 400 by 2008.

In 2007, Alberta declared P. brassicae a pest via the foundation legislation in hopes to help contain spread of the disease. [15]

The Pathotype 3, is the predominant source for Alberta outbreaks. Studies showed that out of the 13 strains of P. brassicae, the most virulent form is dominant in Alberta.

Studies have shown that infestation numbers are highest at common field entrances and decline as you move further into the field, away from the entrance. From these results, it was concluded that infested soil on farm machinery was increasing spread of the pathogen. Some natural field to field spread is starting to be seen [16]

Liming has been an effective control measure to curb clubroot since the 19th century. This method does not eradicate clubroot but it will slow its development by creating unfavorable conditions. In addition, calcium and magnesium can be added to the nutrition profile of the soil to help control clubroot. To get efficient results the field soil, [pH] must be kept above 7.5. This takes massive applications to field soil in order to treat all of the soil where spores of clubroot are found. Combining lime with one other treatment has shown most effective. [17]

Several strains of canola have been tried, including European winter canola cv. Mendel (Brassica napus), as a clubroot-resistant crop. It has been found that few cultivators exist. Specific genotypes do exist, of the Mendel strain, which could be a solution for canola crops in the Canadian prairies. [18]

Crop rotation with non-host crops is another method to help prevent clubroot. The half life of P. brassicae is 3.6 years. Unfortunately, long rotations of approximately 20 years are required in order to be effective. This is very difficult with typical canola rotations not being more than three years. Canola crop brings in high revenue to farmers. This would also require complete removal of Cruciferae crops, such as wild radish and mustard. [19]

Some fungicide has been found to help with clubroot but it is very pricey and would take huge amounts to saturate the soil. The best way to prevent contamination between fields is to clean agricultural equipment and vehicles which have come in contact with club root before moving to a new field. All contaminated soil, equipment and tools must not be moved to clean, disease-free fields. The best preventative method is field monitoring. Throughout the season, plants should be monitored for early symptoms of club root. More research is being conducted for early detection of club root in fall soils. [20]

Related Research Articles

<span class="mw-page-title-main">Plant disease</span> Diseases of plants

Plant diseases are diseases in plants caused by pathogens and environmental conditions. Organisms that cause infectious disease include fungi, oomycetes, bacteria, viruses, viroids, virus-like organisms, phytoplasmas, protozoa, nematodes and parasitic plants. Not included are ectoparasites like insects, mites, vertebrates, or other pests that affect plant health by eating plant tissues and causing injury that may admit plant pathogens. The study of plant disease is called plant pathology.

Northern root-knot nematode is a species of vegetable pathogens which produces tiny galls on around 550 crop and weed species. They invade root tissue after birth. Females are able to lay up to 1,000 eggs at a time in a large egg mass. By surviving harsh winters, they can survive in cold climates.

<span class="mw-page-title-main">Phytomyxea</span> Class of protists

The Phytomyxea are a class of parasites that are cosmopolitan, obligate biotrophic protist parasites of plants, diatoms, oomycetes and brown algae. They are divided into the orders Plasmodiophorida and Phagomyxida. Plasmodiophorids are best known as pathogens or vectors for viruses of arable crops.

Phytophthora sojae is an oomycete and a soil-borne plant pathogen that causes stem and root rot of soybean. This is a prevalent disease in most soybean growing regions, and a major cause of crop loss. In wet conditions the pathogen produces zoospores that move in water and are attracted to soybean roots. Zoospores can attach to roots, germinate, and infect the plant tissues. Diseased roots develop lesions that may spread up the stem and eventually kill the entire plant. Phytophthora sojae also produces oospores that can remain dormant in the soil over the winter, or longer, and germinate when conditions are favourable. Oospores may also be spread by animals or machinery.

<i>Phytophthora palmivora</i> Species of single-celled organism

Phytophthora palmivora is an oomycete that causes bud-rot of palms, fruit-rot or kole-roga of coconut and areca nut. These are among the most serious diseases caused by fungi and moulds in South India. It occurs almost every year in Malnad, Mysore, North & South Kanara, Malabar and other areas. Similar diseases of palms are also known to occur in Sri Lanka, Mauritius, and Sumatra. The causative organism was first identified as P. palmivora by Edwin John Butler in 1917.

<i>Plasmodiophora brassicae</i> A soilborne fungus

Plasmodiophora brassicae is a soilborne organism that is best known for its high economic impact on Brassica oil and vegetable crops. It infects 30 different cruciferous plants, which consists of up to 16 crop species, 9 ornamentals, and 5 weeds. The fungus on those plants causes a disease referred to as clubroot.

<span class="mw-page-title-main">Powdery scab</span> Disease of potatoes

Powdery scab is a disease of potato tubers. It is caused by the cercozoan Spongospora subterranea f. sp. subterranea and is widespread in potato growing countries. Symptoms of powdery scab include small lesions in the early stages of the disease, progressing to raised pustules containing a powdery mass. These can eventually rupture within the tuber periderm. The powdery pustules contain resting spores that release anisokont zoospores to infect the root hairs of potatoes or tomatoes. Powdery scab is a cosmetic defect on tubers, which can result in the rejection of these potatoes. Potatoes which have been infected can be peeled to remove the infected skin and the remaining inside of the potato can be cooked and eaten.

<i>Phytophthora cactorum</i> Species of single-celled organism

Phytophthora cactorum is a fungal-like plant pathogen belonging to the Oomycota phylum. It is the causal agent of root rot on rhododendron and many other species, as well as leather rot of strawberries.

Phytophthora nicotianae or black shank is an oomycete belonging to the order Peronosporales and family Peronosporaceae.

Pythium irregulare is a soil borne oomycete plant pathogen. Oomycetes, also known as "water molds", are fungal-like protists. They are fungal-like because of their similar life cycles, but differ in that the resting stage is diploid, they have coenocytic hyphae, a larger genome, cellulose in their cell walls instead of chitin, and contain zoospores and oospores.

Urocystis brassicae is a gall smut and a plant pathogen that stunts the infected plants. It is known to create root galls on Indian Mustard and other Brassica species.

Verticillium longisporum, also known as Verticillium Wilt, is a fungal plant pathogen that commonly infects canola. V. longisporum can attack other brassica plants as well as woody ornamentals. A main symptom of the infected plant is wilting. In America, V. longsiporum primarily effects eudicot plants. This pathogen can be very devastating and hard to eradicate, responding only to expensive fumigation or fungal resistant plants.

<i>Albugo</i> Genus of plant-parasitic oomycetes

Albugo is a genus of plant-parasitic oomycetes. Those are not true fungi (Eumycota), although many discussions of this organism still treat it as a fungus. The taxonomy of this genus is incomplete, but several species are plant pathogens. Albugo is one of three genera currently described in the family Albuginaceae, the taxonomy of many species is still in flux.

<i>Pratylenchus penetrans</i> Species of roundworm

Pratylenchus penetrans is a species of nematode in the genus Pratylenchus, the lesion nematodes. It occurs in temperate regions worldwide, regions between the subtropics and the polar circles. It is an animal that inhabits the roots of a wide variety of plants and results in necrotic lesions on the roots. Symptoms of P. penetrans make it hard to distinguish from other plant pathogens; only an assay of soil can conclusively diagnose a nematode problem in the field. P. penetrans is physically very similar to other nematode species, but is characterized by its highly distinctive mouthpiece. P. penetrans uses its highly modified mouth organs to rupture the outer surface of subterranean plant root structures. It will then enter into the root interior and feed on the plant tissue inside. P. penetrans is considered to be a crop parasite and farmers will often treat their soil with various pesticides in an attempt to eliminate the damage caused by an infestation. In doing this, farmers will also eliminate many of the beneficial soil fauna, which will lead to an overall degradation of soil quality in the future. Alternative, more environmentally sustainable methods to control P. penetrans populations may be possible in certain regions.

<span class="mw-page-title-main">Napa cabbage</span> Subspecies of flowering plant

Napa cabbage is a type of Chinese cabbage originating near the Beijing region of China that is widely used in East Asian cuisine. Since the 20th century, it has also become a widespread crop in Europe, the Americas and Australia. In much of the world, it is referred to as "Chinese cabbage". In Australia it is sometimes referred to as "wombok".

<i>Plasmodiophora</i> Genus of single-celled organisms

Plasmodiophora is a genus in class Phytomyxea.

<span class="mw-page-title-main">Common scab</span> Plant disease affecting potatoes and other crops

Common scab is a plant disease of root and tuber crops caused by a small number of Streptomyces species, specifically S. scabies, S. acidiscabies, S. turgidiscabies and others. Common scab mainly affects potato, but can also cause disease on radish, parsnip, beet, and carrot. This plant disease is found wherever these vegetables are grown.

Alternaria black spot of canola or grey leaf spot is an ascomycete fungal disease caused by a group of pathogens including: Alternaria brassicae, A. alternata and A. raphani. This pathogen is characterized by dark, sunken lesions of various size on all parts of the plant, including the leaves, stem, and pods. Its primary economic host is canola. In its early stages it only affects the plants slightly by reducing photosynthesis, however as the plant matures it can cause damage to the seeds and more, reducing oil yield as well.

<i>Alternaria brassicicola</i> Species of fungus

Alternaria brassicicola is a fungal necrotrophic plant pathogen that causes black spot disease on a wide range of hosts, particularly in the genus of Brassica, including a number of economically important crops such as cabbage, Chinese cabbage, cauliflower, oilseeds, broccoli and canola. Although mainly known as a significant plant pathogen, it also contributes to various respiratory allergic conditions such as asthma and rhinoconjunctivitis. Despite the presence of mating genes, no sexual reproductive stage has been reported for this fungus. In terms of geography, it is most likely to be found in tropical and sub-tropical regions, but also in places with high rain and humidity such as Poland. It has also been found in Taiwan and Israel. Its main mode of propagation is vegetative. The resulting conidia reside in the soil, air and water. These spores are extremely resilient and can overwinter on crop debris and overwintering herbaceous plants.

<span class="mw-page-title-main">Alternaria leaf spot</span> Fungal plant disease

Alternaria leaf spot or Alternaria leaf blight are a group of fungal diseases in plants, that have a variety of hosts. The diseases infects common garden plants, such as cabbage, and are caused by several closely related species of fungi. Some of these fungal species target specific plants, while others have been known to target plant families. One commercially relevant plant genus that can be affected by Alternaria Leaf Spot is Brassica, as the cosmetic issues caused by symptomatic lesions can lead to rejection of crops by distributors and buyers. When certain crops such as cauliflower and broccoli are infected, the heads deteriorate and there is a complete loss of marketability. Secondary soft-rotting organisms can infect stored cabbage that has been affected by Alternaria Leaf Spot by entering through symptomatic lesions. Alternaria Leaf Spot diseases that affect Brassica species are caused by the pathogens Alternaria brassicae and Alternaria brassicicola.

References

  1. ↑ Culture of Vegetables and Flowers. 1921. Archived from the original on 2006-03-16. Retrieved 2006-04-04.
  2. ↑ Javed, Muhammad Asim; Schwelm, Arne; Zamani-Noor, Nazanin; Salih, Rasha; Vañó, Marina Silvestre; Wu, Jiaxu; González García, Melaine; Heick, Thies Marten; Luo, Chaoyu; Prakash, Priyavashini; Pérez-López, Edel (2022). "The clubroot pathogen Plasmodiophora brassicae: A profile update". Molecular Plant Pathology. 24 (2): 89–106. doi:10.1111/mpp.13283. PMC   9831288 . PMID   36448235.
  3. ↑ Schwelm, Arne; Badstöber, Julia; Bulman, Simon; Desoignies, Nicolas; Etemadi, Mohammad; Falloon, Richard E.; Gachon, Claire M. M.; Legreve, Anne; Lukeš, Julius; Merz, Ueli; Nenarokova, Anna; Strittmatter, Martina; Sullivan, Brooke K.; Neuhauser, Sigrid (2018). "Not in your usual Top 10: Protists that infect plants and algae". Molecular Plant Pathology. 19 (4): 1029–1044. doi:10.1111/mpp.12580. PMC   5772912 . PMID   29024322.
  4. ↑ Schwelm A, Fogelqvist J; Knaust A; et al. (2015). "The Plasmodiophora brassicae genome reveals insights in its life cycle and ancestry of chitin synthases". Scientific Reports. 5: 11153. Bibcode:2015NatSR...511153S. doi:10.1038/srep11153. PMC   4471660 . PMID   26084520.
  5. ↑ Christianson, J. (2008). Club Root of Crucifers. University of Nebraska-Lincoln. Retrieved from "Club Root of Crucifers Key words: Plant Disease, Plasmodiophora brassicae, cabbage, Chinese cabbage, Brussels sprouts, turnips, wormseed mustard black mustard, tumble mustard, kohlrabi, collards, kale, broccoli, cauliflower, rutabaga, sea kale, radish, rape candytuft". Archived from the original on 2010-07-23. Retrieved 2012-03-22. Mar 2012
  6. ↑ Hybrid Vegetable Development, by P. K. Singh (Ed.), S. K. Dasgupta (Ed.), S. K. Tripathi (Ed.), Haworth Press. ISBN   1-56022-118-6
  7. ↑ NC State University Department of Plant Pathology Archived 2005-12-17 at the Wayback Machine (accessed 27 October 2005)
  8. ↑ Clubroot in the cole crops: the interaction between Plasmodiophora brassicae and Brassica oleracea
  9. 1 2 3 Charles W. Averre. "Club-Root of Cabbage and Related Crops". Vegetable Disease Information Note 17 (VDIN-0017). North Carolina State University. Archived from the original on July 21, 2010. Retrieved October 26, 2010.
  10. 1 2 George N. Agrios (2005). Plant Pathology (5th ed.). Burlington, MA: Academic Press. ISBN   978-0-12-044565-3.
  11. 1 2 "Clubroot of Cabbage. Plasmodiophora brassicae". Plant Disease Diagnostic Clinic. Cornell University. Archived from the original on August 22, 2010. Retrieved October 26, 2010.
  12. 1 2 "Clubroot Disease of Canola and Mustard". Government of Alberta Agriculture and Rural Development. November 23, 2007. Archived from the original on December 9, 2010. Retrieved October 26, 2010.
  13. ↑ Lindsey J. du Toit. "Clubroot of cabbage and other crucifers" (PDF). Washington State University. Archived from the original (PDF) on June 6, 2010. Retrieved October 26, 2010.
  14. 1 2 "Coping with Club Root - Plasmodiophora brassicae". Allotment Vegetable Growing. Archived from the original on October 25, 2010. Retrieved October 26, 2010.
  15. ↑ Cao T.; et al. (2010). "Virulence and spread of Plasmodiophora brassicae [clubroot] in Alberta Canada". Canadian Journal of Plant Pathology. 31 (3): 321–329. doi:10.1080/07060660909507607. S2CID   85839391.
  16. ↑ Cao T.; et al. (2010). "Virulence and spread of "Plasmodiophora brassicae" clubroot in Alberta Canada". Canadian Journal of Plant Pathology. 31 (3): 321–329. doi:10.1080/07060660909507607. S2CID   85839391.
  17. ↑ Kowata-Dresch, L.S., May-De Milo, L.L. (2012). Clubroot Management of Highly Infested Soils. "Crop Protection, 35, p47-52." doi : 10.1016/j.cropro.2011.12.012
  18. ↑ Rahman, H., Shakir, A., Hasan, MJ. (2011). Breeding for clubroot resistant spring canola (Brassica napus L.) for the Canadian Prairies: Can the European winter canola cv. Mendel be used as a source for resistance. " Canadian Journal of Plant Science 91(3), p.447-458." doi : 10.4141/CJPS10073
  19. ↑ Donald C., Porter I. (2009). "Integrated Control of Clubroot". Journal of Plant Growth and Regulation. 28 (3): 289–303. doi:10.1007/s00344-009-9094-7. S2CID   25458971.
  20. ↑ Trembly, N., et al. (1999). Clubroot of Crucifiers: Control Strategies. "Agriculture and Agrifood Canada." Retrieved from http://publications.gc.ca/collections/Collection/A42-85-1999E.pdf March 2012.
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