Helminthosporium solani

Last updated
Silver scurf blemishes on a tuber Silver Scurf H. solani.JPG
Silver scurf blemishes on a tuber

Helminthosporium solani
Solanum tuberosum 'Nicola', aardappel.jpg
A tuber with silver scurf blemishes
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Fungi
Division: Ascomycota
Class: Dothideomycetes
Order: Pleosporales
Family: Massarinaceae
Genus: Helminthosporium
Species:
H. solani
Binomial name
Helminthosporium solani
Synonyms [1]
  • Brachysporium solani (Durieu & Mont.) Sacc.
  • Dematium atrovirens Harz
  • Spondylocladium atrovirens (Harz) Harz ex Sacc.
  • Helminthosporium atrovirens (Harz) E.W. Mason & S. Hughes

Helminthosporium solani is a fungal plant pathogen responsible for the plant disease known as silver scurf. Silver scurf is a blemish disease, meaning the effect it has on tubers is mostly cosmetic and affects "fresh market, processing and seed tuber potatoes." [2] There are some reports of it affecting development, meaning growth and tuber yield. This is caused by light brown lesions, which in turn change the permeability of tuber skin and then it causes tuber shrinkage and water loss, which finally causes weight loss. [2] The disease has become economically important because silver scurf affected potatoes for processing and direct consumption have been rejected by the industry. [2] The disease cycle can be divided into two stages: field and storage. It is mainly a seed borne disease and the primary source of inoculum is mainly infected potato seed tubers. Symptoms develop and worsen in storage because the conditions are conducive to sporulation. The ideal conditions for the spread of this disease are high temperatures and high humidity. There are also many cultural practices that favor spread and development. There are multiple ways to help control the disease.

Contents

Signs and symptoms

Silver scurf blemishes on a tuber Silver Scurf (H. solani).JPG
Silver scurf blemishes on a tuber

Silver scurf is a plant disease of potato, which is caused by the anamorphic ascomycete fungus, Helminthosporium solani. Potato tubers are the only known host of Helminthosporium solani. It is a highly specific pathogen which does not have a secondary host or alternate host. A common symptom of this disease is blemishing on the surface of the potato tubers. These blemishes are tan and/or gray due to a loss of pigment, and they are usually irregularly shaped. Also, a post-harvest symptom can be shrinkage and shriveling of the outer tissue of the potato due to water loss. [3] Black spots can also be found on the surface of infected tubers, which are a sign of the disease. These are made up of conidia and conidiophores of the pathogenic fungus. [4] The conidia are characterized by being very darkly melanized and having multiple pseudosepta. Another characteristic of this fungus is the absence of motile spores.

Like with many other fungal plant diseases, a diagnosis can be made by looking for the specific sexual structures of the fungus and observing them for the specific characteristics of silver scurf. [4] Another way that silver scurf can be diagnosed is through molecular techniques, such as PCR and sequencing to identify the presence of the pathogen. The primer pair, HSF19-HSR447, has been generated to be specific for amplifying only a section of Helminthosporium solani DNA. [5]

Currently, no known host factors have been identified that have been linked to increase susceptibility or development of the disease. It seems as though the environmental conditions are what plays a major role in severity of the disease.

Disease cycle

The disease cycle of silver scurf can be divided in two phases (field and storage). [2] The primary source of inoculum is infected potato seed tubers. This inoculum is then transferred to the daughter tubers through an unknown mechanism, although indirect evidence suggests it happens when they come in direct contact or close proximity to daughter tubers. [2] Conidia produced on the surface of seed tubers are dispersed by rain or irrigation to uninfected tubers. These conidia germinate and infect tubers. The pathogen enters through the periderm or lenticels. After that, the pathogen colonizes the periderm cells in the tuber. Infection may happen when tubers are formed and can continue in the season. [6] In harvest (mostly in summer), silver scurf symptoms are not too apparent. However, the symptoms develop and worsen due relatively humid and warm temperatures in storage, since these conditions are conducive to sporulation. [2] Secondary inoculum is produced by conidia, which can spread in storage by wind of ventilation while the tubers are in storage. When a seed tuber from this storage is planted, this can then carry inoculum to the field. [4] It was believed that overwintering soil-borne inoculum wasn’t important in the disease cycle, but recent studies suggest H.solani may survive in the soil for a short period of time, which can cause more infection. [4]

This is an imperfect fungus and its teleomorph has not been described. [2] Disease symptoms appear on tubers, but not on the haulm (vine) or roots, and are limited to the periderm, composed of phellem, phelloderm and cortical layers that replace the epidermis of the tuber. [7] See next section (Environment) to understand the occurrence and severity of the different stages of the life cycle mentioned here.

Environment

There are a number of conditions that favor the spread and development of H. solani. Usually, the temperature range of 15 – 32 °C combined with high humidity increase conidial germination. [2] In addition to this, there are many cultural practices which affect the conditions that favor disease spread and development. These practices include: the level of H. solani present on the seed, planting and harvesting dates, crop rotations and warehouse management. [4] It has been demonstrated [8] that later harvest dates increase the development of the disease. It has also been demonstrated that the disease was more severe when planting densities were higher. [4] All of these factors combined have an effect of disease spread and development.

Pathogenesis

The spores can still infect and cause disease in daughter tubers in the soil for about two years. [3] It is also possible for the pathogen to spread by growing through the roots of a potato plant to the developing tubers and cause infection. H. solani conidia are found on the outside of potato tubers, and the hyphae enter the tuber to cause disease. The pathogen can enter the tissue through wounds or natural openings, as well as being able to directly penetrate the periderm with the use of an appressorium and penetration peg. [9] The fungus is contained in the outer layers of the potato and cannot infect very deep into the tuber. The discoloration on the periderm of the potato is formed from the loss of pigmentation caused by extreme dryness of the cell and suberin deposition. [10] Not much is currently known about the molecular aspects of the mechanism for spread and infection of the disease, but there is currently ongoing research on this pathogen to gain a better understanding. [4]

Disease control

Chemical control

Fungicides control many plant diseases efficiently, but very limited types of fungicides are efficient against the silver scurf pathogen. [11] Fungicides usually apply to soil or seed tubers before culturing.

Thiabendazole (TBZ) fungicide

TBZ is widely used as post-harvest treatment on potatoes since the early 1970s. [11] Silver scurf on tubers can be reduced by the systemic broad-spectrum fungicide TBZ. [12] TBZ is low toxicity and is used to prevent or control silver scurf for short time period, e.g. several months, with no effect on quality or retention of residues. [12]

TBZ-resistant H. solani isolates

The TBZ fungicide used to be very effective until 1977 when TBZ-resistant H. solani isolates were found in potato stores, as post-harvest treatment. [13] TBZ resistance in H. solani resulted from a point mutation of a single base at codon 198 from glutamic acid to glutamine, or alanine, in the b-tubulin. [14] This mutation functions in avoiding TBZ and other benzimidazole fungicides from binding to the H. solani b-tubulin gene thus results in TBZ-resistant phenotypes. [11]

Fungicides besides TBZ

As the frequency of resistant isolates to TBZ increase, some other fungicides have been tested to control silver scurf, such as imazalil, prochloraz and propiconazole fungicides, which are all classified in conazole, DMI (demethylation inhibitors). Imazalil and prochloraz fungicides are commonly used in seed treatment, while propiconazole fungicide is usually for foliar treatment.

Host resistance

One of the major reasons for the increasing economic importance of silver scurf is the lack of high levels of resistance in potato cultivars. [8] [11] [15]

Interspecific crosses with wild Solanum species have been used to increase disease resistance in cultivars of S. tuberosum. Genes from the wild tuber-bearing species Solanum demissum , Solanum chacoense and Solanum aculae , which have low sporulation of H. solani, have been incorporated into the background of some Canadian potato cultivars. [16] [17] These interspecific crosses and advanced selections are being screened for resistance to different diseases including silver scurf. [17] [18] However, no silver scurf-resistant cultivars of Solanum tuberosum have, thus far, been identified. [11] There is lack of reports of silver scurf resistant potato cultivars. [4]

Suppressive soils

Soil types influenced the development of silver scurf to a great extent, both at harvest season and the following three-month storage period. Some soils displayed suppressiveness in different levels. [19] The results from experimental trials revealed a significant negative correlation between silver scurf disease severity, and soil NO3 content and Fe availability. NO3 had been negatively correlated with silver scurf disease previously. [20] This provides a possible suppressive effect of these two soil components. [20] NO3 is an efficient nitrogen source used by H. solani. [21] Therefore, a direct adverse effect between silver scurf and NO3 is not likely to happen. A probable explanation for this observation is that NO3 could function on other soil microorganisms [19] which possibly act as H. solani antagonists. [19] These results indicated that microbial antagonists may be the key components contributing to soil suppressiveness and their antagonists may lead efficient biological control of silver scurf. [19]

Biological control

Biological control is considered an attractive alternative to chemicals for the efficient, reliable, and environmentally safe control of plant pathogens. [4]

A fungus of the genus Cephalosporium (now renamed Acremonium strictum ) was able to decrease the dissemination of silver scurf in storage. Cephalosporium has shown the ability to significantly diminish sporulation, spore germination and mycelial growth of H. solani. [22] However, Cephalosporium does not reduce silver scurf on previously infected potatoes. [22]

In laboratory experiments, isolations from potato growing soil and the rhizosphere of potato plants during sprouting, Trichoderma hamatum , Trichoderma koningii , Trichoderma polysporum , Trichoderma harzianum and Trichoderma viride were the most inhibitory microorganisms to H. solani growth in vitro. [23]

Achromobacter piechaudii , Bacillus cereus , Cellulomonadaceae fimi , Pseudomonas chlororaphis , Pseudomonas fluorescens , Pseudomonas putidaputida , and Streptomyces griseus were able to inhibit mycelial growth and/or conidial germination through the production of diffusible metabolites and that antibiosis was likely responsible fully or partially for their antagonism of H. solani. [24]

Biopesticides

Serenade ASO (a formulation of Bacillus subtilis ) has proved to suppress silver scurf, reduced both the incidence and severity of silver scurf under low disease pressure and delayed the beginning of silver scurf in storage for five months.[ citation needed ]

Relevance

When silver scurf was first found in Moscow in 1871, it was considered as a minor plant disease. [2] After an increase in silver scurf incidence from America, Europe, Middle East, Africa, China, and New Zealand since 1968, the disease was later considered a pathogen of major importance. Although the disease did not cause potato yield losses and only affected the cosmetic appearance of the tuber, it had a huge impact on the potato market. [4] With growing consumer demands for attractive appearance in fresh market cultivars, silver scurf on potatoes with blemishes and discoloration have been rejected by the industry. Furthermore, the silver scurf causes water loss which makes it difficult to peel the tubers. The excess tuber shrinkage also causes weight loss in tubers. [25] From the cosmetic effect, dehydration, and weight loss of the tubers, the fresh market is facing major economic losses from the disease even today. For example, the Idaho's potato industry lost about 7 to 8.5 million dollars from the silver scurf disease. [26] Not only does the cost come from rejecting silver scurf diseased potatoes, but it also comes from an increase in the amount of time needed for sorting and inspecting every potato.

Related Research Articles

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

Phytophthora infestans is an oomycete or water mold, a fungus-like microorganism that causes the serious potato and tomato disease known as late blight or potato blight. Early blight, caused by Alternaria solani, is also often called "potato blight". Late blight was a major culprit in the 1840s European, the 1845–1852 Irish, and the 1846 Highland potato famines. The organism can also infect some other members of the Solanaceae. The pathogen is favored by moist, cool environments: sporulation is optimal at 12–18 °C (54–64 °F) in water-saturated or nearly saturated environments, and zoospore production is favored at temperatures below 15 °C (59 °F). Lesion growth rates are typically optimal at a slightly warmer temperature range of 20 to 24 °C.

<i>Botrytis cinerea</i> Species of fungus

Botrytis cinerea is a necrotrophic fungus that affects many plant species, although its most notable hosts may be wine grapes. In viticulture, it is commonly known as "botrytis bunch rot"; in horticulture, it is usually called "grey mould" or "gray mold".

<span class="mw-page-title-main">Fusarium wilt</span> Fungal plant disease

Fusarium wilt is a common vascular wilt fungal disease, exhibiting symptoms similar to Verticillium wilt. This disease has been investigated extensively since the early years of this century. The pathogen that causes Fusarium wilt is Fusarium oxysporum. The species is further divided into formae speciales based on host plant.

<i>Trichoderma viride</i> Species of fungus

Trichoderma viride is a fungus and a biofungicide.

<i>Rhizoctonia solani</i> Species of fungus

Rhizoctonia solani is a species of fungus in the order Cantharellales. Basidiocarps are thin, effused, and web-like, but the fungus is more typically encountered in its anamorphic state, as hyphae and sclerotia. The name Rhizoctonia solani is currently applied to a complex of related species that await further research. In its wide sense, Rhizoctonia solani is a facultative plant pathogen with a wide host range and worldwide distribution. It causes various plant diseases such as root rot, damping off, and wire stem. It can also form mycorrhizal associations with orchids.

Alternaria triticina is a fungal plant pathogen that causes leaf blight on wheat. A. triticina is responsible for the largest leaf blight issue in wheat and also causes disease in other major cereal grain crops. It was first identified in India in 1962 and still causes significant yield loss to wheat crops on the Indian subcontinent. The disease is caused by a fungal pathogen and causes necrotic leaf lesions and in severe cases shriveling of the leaves.

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

Phytophthora erythroseptica—also known as pink rot along with several other species of Phytophthora—is a plant pathogen. It infects potatoes causing their tubers to turn pink and damages leaves. It also infects tulips (Tulipa) damaging their leaves and shoots.

<i>Stemphylium solani</i> Species of fungus

Stemphylium solani is a plant pathogen fungus in the phylum Ascomycota. It is the causal pathogen for grey leaf spot in tomatoes and leaf blight in alliums and cotton, though a wide range of additional species can serve as hosts. Symptoms include white spots on leaves and stems that progress to sunken red or purple lesions and finally leaf necrosis. S. solani reproduces and spreads through the formation of conidia on conidiophores. The teleomorph name of Stemphyllium is Pleospora though there are no naturally known occurrences of sexual reproduction. Resistant varieties of tomato and cotton are common, though the pathogen remains an important disease in Chinese garlic cultivation.

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

Alternaria solani is a fungal pathogen that produces a disease in tomato and potato plants called early blight. The pathogen produces distinctive "bullseye" patterned leaf spots and can also cause stem lesions and fruit rot on tomato and tuber blight on potato. Despite the name "early," foliar symptoms usually occur on older leaves. If uncontrolled, early blight can cause significant yield reductions. Primary methods of controlling this disease include preventing long periods of wetness on leaf surfaces and applying fungicides. Early blight can also be caused by Alternaria tomatophila, which is more virulent on stems and leaves of tomato plants than Alternaria solani.

Acremonium strictum is an environmentally widespread saprotroph species found in soil, plant debris, and rotting mushrooms. Isolates have been collected in North and Central America, Asia, Europe and Egypt. A. strictum is an agent of hyalohyphomycosis and has been identified as an increasingly frequent human pathogen in immunosuppressed individuals, causing localized, disseminated and invasive infections. Although extremely rare, A. strictum can infect immunocompetent individuals, as well as neonates. Due to the growing number of infections caused by A. strictum in the past few years, the need for new medical techniques in the identification of the fungus as well as for the treatment of human infections has risen considerably.

<i>Colletotrichum coccodes</i> Pathogenic fungus

Colletotrichum coccodes is a plant pathogen, which causes anthracnose on tomato and black dot disease of potato. Fungi survive on crop debris and disease emergence is favored by warm temperatures and wet weather.

<i>Septoria malagutii</i> Species of fungus

Septoria malagutii is a fungal plant pathogen infecting potatoes. The casual fungal pathogen is a deuteromycete and therefore has no true sexual stage. As a result, Septoria produces pycnidia, an asexual flask shaped fruiting body, on the leaves of potato and other tuber-bearing spp. causing small black to brown necrotic lesions ranging in size from 1-5mm. The necrotic lesions can fuse together forming large necrotic areas susceptible to leaf drop, early senescence, dieback, and dwarfing. Septoria malagutii has been found only in the Andean countries of Bolivia, Ecuador, Peru, and Venezuela at altitudes of near 3000 meters. Consequently, the fungi grows and disperses best under relatively low temperatures with high humidities, with optimal growth occurring at 20 °C (68 °F). The disease has caused devastation on potato yields in South America and in areas where this disease is common, potato yields have been seen to drop by 60%.

Rhizopus soft rot is a disease of the sweet potato. It is one of the most common to affect the sweet potato, happening during packing and shipping. The disease causes a watery soft rot of the internal portion of the storage root. Strategies to manage the disease include the development of resistant varieties, curing through the use of heat and humidity, and application of decay control products.

<i>Dickeya solani</i> Species of bacterium

Dickeya solani is a bacterium that causes blackleg and soft rot in potato crops. Its symptoms are often indistinguishable from those caused by Pectobacterium but is more virulent, causing disease from lower levels of inoculum and spreading through the plant more effectively.

<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.

Fusarium dry rot is one of the most common potato diseases. It is caused by fungi in the genus Fusarium. This fungi causes a variety of colored rots in potatoes. This pathogen, while having both a sexual and asexual form, stays in an asexual cycle due to the way it spreads. Preferring warmer climates, it is not uncommon to find this pathogen in the northern United States where it has been reported to affect yield as much as 60%.

Black pod disease is a fungal disease of Cocoa trees. It is mostly found in tropical areas where cocao trees grow, and its spores are spread via the heavy rainfalls that can occur in tropical climates. Annually, the pathogen can cause a yield loss of up to 1/3, and up to 10% of total trees can be lost completely.

<span class="mw-page-title-main">Blackleg (potatoes)</span> Bacterial disease of potato plants

Blackleg is a plant disease of potato caused by pectolytic bacteria that can result in stunting, wilting, chlorosis of leaves, necrosis of several tissues, a decline in yield, and at times the death of the potato plant. The term "blackleg" originates from the typical blackening and decay of the lower stem portion, or "leg", of the plant.

Black dot disease is caused by the plant pathogen known as Colletotrichum coccodes. It affects all underground parts of the potato, including the roots, tuber, and stolon. C. coccodes is also able to infect the stem and foliage of the potato plant. It can be introduced into an area by planting an infected tuber, and then spreading to other plants. A sign of black dot disease is black microsclerotia that are produced by the pathogen, and can be found on the roots, the tuber, the stems, and the leaves. This can be used to diagnose black dot. Symptoms of black dot disease include silvery lesions on the surface of the tuber, brown or black lesions on the leaves, leaf wilting, and chlorosis.

<span class="mw-page-title-main">Viral diseases of potato</span> Group of diseases affecting potato plants

Viral diseases of potato are a group of diseases caused by different types of Viruses that affect potato crops worldwide and, although they do not affect human or animal health since they are viruses that only infect vegetables, they are a source of great economic losses annually. About 28 viruses have been reported infecting potato crops. However, potato virus X (PVX), potato virus Y (PVY), and potato leafroll virus (PLRV) are the most important viruses worldwide. Some others are of economic importance only in some regions. Such is the case of potato virus M (PVM) in some Asian and European countries.

References

  1. ↑ Helminthosporium solani in Index Fungorum
  2. 1 2 3 4 5 6 7 8 9 Errampalli, D.; Saunders, J. M.; Holley, J. D. (2001). "Emergence of silver scurf (Helminthosporium solani) as an economically important disease of potato". Plant Pathology. 50 (2): 141. doi:10.1046/j.1365-3059.2001.00555.x.
  3. 1 2 Shetty, Kiran. "University of Idaho Extension" (PDF). Silver Scurf of Potatoes. Retrieved 2015-10-21.
  4. 1 2 3 4 5 6 7 8 9 10 Avis, T. J.; Martinez, C.; Tweddell, R. J. (2010-09-02). "Minireview/Minisynthèse Integrated management of potato silver scurf (Helminthosporium solani)". Canadian Journal of Plant Pathology. 32 (3): 287–297. doi:10.1080/07060661.2010.508627. ISSN   0706-0661. S2CID   49177264.
  5. ↑ Olivier, Claudia; Loria, Rosemary (1998-11-01). "Detection of Helminthosporium solani from soil and plant tissue with species-specific PCR primers". FEMS Microbiology Letters. 168 (2): 235–241. doi: 10.1111/j.1574-6968.1998.tb13279.x . ISSN   1574-6968.
  6. ↑ "Silver Scurf of Potato fact sheet". vegetablemdonline.ppath.cornell.edu. Retrieved 2015-10-20.
  7. ↑ Fahn A, ed., 1982. Plant Anatomy. Exeter, UK: Wheaton.
  8. 1 2 MÉRIDA, C.L., LORIA, R., & HALSETH, D.E. (1994). Effects of potato cultivar and time of harvest on the severity of silver scurf. Plant Dis., 78, 146–149.
  9. ↑ Hamm, P.B. (August 2007). "Silver Scurf Management in Potatoes" (PDF).{{cite journal}}: Cite journal requires |journal= (help)
  10. ↑ Errampalli, D; Saunders, J. (2001). "Emergence of silver scurf (Helminthosporium solani) as an economically important disease of potato". Plant Pathology. 50 (2): 141–153. doi:10.1046/j.1365-3059.2001.00555.x.
  11. 1 2 3 4 5 Errampalli, D.; Saunders, J. M.; Holley, J. D. (2001-04-01). "Emergence of silver scurf (Helminthosporium solani) as an economically important disease of potato". Plant Pathology. 50 (2): 141–153. doi:10.1046/j.1365-3059.2001.00555.x. ISSN   1365-3059.
  12. 1 2 Hide GA, Hirst JM, Griffith RL, 1969a. Control of potato tuber diseases with systemic fungicides. In: Proceedings of the Fifth British Insecticide and Fungicide Conference, Brighton. Croydon, UK: British Crop Protection Council, 310-4.
  13. ↑ Hide, G. A.; Hall, Sharon M.; Boorer, Kathryn J. (1988-09-01). "Resistance to thiabendazole in isolates of Helminthosporium solani, the cause of silver scurf disease of potatoes". Plant Pathology. 37 (3): 377–380. doi:10.1111/j.1365-3059.1988.tb02088.x. ISSN   1365-3059.
  14. ↑ MKay, G (1997). "A PCR-based method to characterise and identify benzimidazole resistance in Helminthosporium solani". FEMS Microbiology Letters. 152 (2): 371–378. doi:10.1016/s0378-1097(97)00229-2. PMID   9231430.
  15. ↑ RODRIGUEZ, D.A. (1994). Studies on epidemiology and management of silver scurf of potato. PhD Thesis. North Dakota State University, Fargo, ND.
  16. ↑ De Jong H, Tarn TR, 1984. Using germplasm in potato breeding in Canada. Canadian Agriculture 30, 12-4.
  17. 1 2 Murphy AM, De Jong H, Proudfoot KG, 1999. A multiple disease resistant potato clone developed with classical breeding methodology. Canadian Journal of Plant Pathology 21, 207–12.
  18. ↑ Kurowski C, Manzer F, 1992. Re-evaluation of Solanum species accessions showing resistance to bacterial ring rot. American Potato Journal 69, 289-97.
  19. 1 2 3 4 Martinez, C; Michaud, M; Bélanger, R. R; Tweddell, R. J (2002-12-01). "Identification of soils suppressive against Helminthosporium solani, the causal agent of potato silver scurf". Soil Biology and Biochemistry. 34 (12): 1861–1868. doi:10.1016/S0038-0717(02)00199-2.
  20. 1 2 ADAMS, A.P., SANDAR, N., & NELSON, D.C. (1970). Some properties of soils affecting russet scab and silver scurf of potatoes. Am. Potato J., 47, 49–57.
  21. ↑ SINGH, A. (1968). Studies on Helminthosporium solani, the causal organism of silver scurf of potato. PhD Thesis, North Dakota State University, Fargo, ND.
  22. 1 2 Rivera-Varas, Viviana V.; Freeman, Thomas A.; Gudmestad, Neil C.; Secor, Gary A. (2007-09-17). "Mycoparasitism of Helminthosporium solani by Acremonium strictum". Phytopathology. 97 (10): 1331–1337. doi:10.1094/PHYTO-97-10-1331. ISSN   0031-949X. PMID   18943692.
  23. ↑ Kurzawinska, Halina, 2006: An interaction of potato crop soil fungi population on fungi responsible for tuber superficial diseases. Journal of Plant Protection Research 46(4): 339-346
  24. ↑ Martinez, Carole; Avis, Tyler J.; Simard, Jean-Nicolas; Labonté, Jessica; Bélanger, Richard R.; Tweddell, Russell J. (2006). "The role of antibiosis in the antagonism of different bacteria towards Helminthosporium solani, the causal agent of potato silver scurf". Phytoprotection. 87 (2): 69. doi:10.7202/013975ar. S2CID   86008921.
  25. ↑ Franc, Gary. "Silver Scurf of Potato" (PDF). Wyoming Extension. University of Wyoming. Archived from the original (PDF) on March 4, 2016. Retrieved Oct 21, 2015.
  26. ↑ Shetty, Kiran; Franzier, Mary. "Silver Scurf of Potatoes" (PDF). Kimberly Research and Extension Center. University of Idaho. Retrieved Nov 11, 2015.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.