Stem Blight of Eustoma grandiflorum Caused by Sclerotium rolfsii

During a 4-week period in May through June 1996, 15% of 50 mature lisianthus (Eustoma grandiflorum) ‘Maurine Blue’ and ‘Maurine White’ plants exhibited stem blight in a landscape planting in west-central Florida. Initial disease symptoms included stem necrosis at the soil line, and yellowing and tan discoloration of leaves. As blighting of the stem progressed, infected plants wilted and died. Symptomatic stem sections from three plants were surface-disinfested in 0.5% NaOCl and placed on acidified 25% potato dextrose agar (APDA). Sclerotium rolfsii Sacc. was isolated from all three diseased stems. Pathogenicity of each of three S. rolfsii isolates was confirmed using two lisianthus ‘Flamenco Blue’ plants grown in 10.2-cm-diameter plastic pots containing a peat-based medium. Sclerotia produced on APDA were sprinkled on the soil surface around each plant base; 50, 100, and 5 sclerotia from isolates A, B, and C, respectively, were used (isolate C grew more slowly and produced fewer sclerotia than either A or B). Two noninoculated lisianthus served as controls. Plants were maintained in a greenhouse at minimum and maximum temperatures of ≈24 and 35°C, respectively. Plants inoculated with sclerotia from isolates A and B developed blight symptoms within 6 days. One of two plants inoculated with isolate C developed blight symptoms within 17 days, and the other remained symptomless, as did the control plants. Infection by S. rolfsii was confirmed by reisolation from symptomatic tissue. This is the first report of stem blight of lisianthus caused by S. rolfsii.

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Stem Blight of Eustoma grandiflorum Caused by Sclerotium rolfsii in Florida

Plant Health Progress ◽

10.1094/php-2000-0606-01-hn ◽

2000 ◽

Vol 1 (1) ◽

pp. 29

Author(s):

R. J. McGovern ◽

H. Bouzar ◽

B. K. Harbaugh

Keyword(s):

Sclerotium Rolfsii ◽

Eustoma Grandiflorum ◽

Disease Symptoms ◽

Central Florida ◽

Stem Blight ◽

Soil Line ◽

West Central ◽

Stem Necrosis

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First Report of Sclerotium rolfsii on Jerusalem Cherry (Solanum pseudocapsicum) in Europe

Plant Disease ◽

10.1094/pdis.2000.84.9.1048b ◽

2000 ◽

Vol 84 (9) ◽

pp. 1048-1048

Author(s):

A. Garibaldi ◽

A. Minuto ◽

M. L. Gullino

Keyword(s):

United States ◽

Sclerotium Rolfsii ◽

Soil Surface ◽

The United States ◽

Northern Italy ◽

Ornamental Plant ◽

Potato Dextrose Agar ◽

First Report ◽

Initial Symptoms ◽

Stem Necrosis

Jerusalem cherry (Solanum pseudocapsicum) has recently become popular as a potted ornamental plant in Italy. During the summer of 1999, a sudden wilt of 60-day-old plants was observed in the Albenga region (Northern Italy), an area of intensive floriculture. Initial symptoms included stem necrosis at the soil line and yellowing and tan discoloration of leaves. As stem necrosis progressed, infected plants wilted and died. Necrotic tissues were covered with whitish mycelium that differentiated into reddish brown, spherical (1 to 2 mm diameter) sclerotia. Sclerotium rolfsii was consistently recovered from the surface of symptomatic stem sections that were disinfected for 1 min in 1% NaOCl and then plated on potato-dextrose agar (PDA) amended with 100 ppm streptomycin sulfate. Pathogenicity of three S. rolfsii isolates was confirmed by inoculating 90-day-old S. pseudocapsicum plants grown in pots. Inoculum consisted of mycelium and sclerotia of the pathogen placed on the soil surface around the base of each plant. Noninoculated plants served as controls. All plants were kept in a growth chamber at 18 to 28°C and RH > 85%. Inoculated plants developed symptoms within 7 days, while control plants remained symptomless. Sclerotia developed on infected tissues and S. rolfsii was reisolated from symptomatic tissues. The disease has been observed in the United States (1), but this is the first report of stem blight of S. pseudocapsicum caused by S. rolfsii in Europe. Reference: (1) S. A. Alfieri, Jr., K. R. Langdon, C. Wehlburg, and J. W. Kimbrough, J. W. Index Plant Dis. Florida Bull. 11:215, 1984.

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Comparative studies on myceliogenic germination of tan sclerotia of Sclerotinia sclerotiorum and Sclerotium rolfsii

Canadian Journal of Botany ◽

10.1139/b89-184 ◽

1989 ◽

Vol 67 (5) ◽

pp. 1395-1401 ◽

Cited By ~ 3

Author(s):

H. C. Huang ◽

S. K. Sun

Keyword(s):

Sclerotinia Sclerotiorum ◽

Room Temperature ◽

Sclerotium Rolfsii ◽

Soil Surface ◽

Time Lapse ◽

Potato Dextrose Agar ◽

Damping Off ◽

Seed Rot ◽

Myceliogenic Germination ◽

Exogenous Nutrients

Tan-colored sclerotia of Sclerotium rolfsii and of an aberrant strain of Sclerotinia sclerotiorum that were freshly harvested from 5-week-old cultures on potato dextrose agar or stored at room temperature in paper bags for 4 weeks germinated myceliogenically on moist field soil without exogenous nutrients. A comparative study by time-lapse photomicroscopy revealed similarity in the mode of myceliogenic germination of sclerotia of the two species. The germination appeared to be of the hyphal type in both species and was characterized by the emergence of individual hyphae through the rind. There was no evidence of eruptive type of germination in any of the strains tested. Although several hyphae often emerged through the same spot of the rind, these hyphae emerged singly, and the time-lapse photomicrographs showed no evidence of eruptive germination. While most of the germinated sclerotia of S. rolfsii developed into colonies within 4 days of incubation on moist soil, the development of colonies from germinating sclerotia of S. sclerotiorum appeared to be slow, taking up to 28 days. Results of the inoculation studies showed that mycelia from the germinated sclerotia of S. rolfsii were able to infect and cause seed rot and damping-off of canola and alfalfa, which were planted near the soil surface at a distance of at least 15 mm from the sclerotium, without providing exogenous nutrients.

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First Report of Gummy Stem Blight, Caused by Didymella bryoniae, on Watermelon Transplants in California

Plant Disease ◽

10.1094/pdis.1997.81.11.1331b ◽

1997 ◽

Vol 81 (11) ◽

pp. 1331-1331 ◽

Cited By ~ 19

Author(s):

S. T. Koike

Keyword(s):

Citrullus Lanatus ◽

Potato Dextrose Agar ◽

Fruiting Bodies ◽

Didymella Bryoniae ◽

Dark Cycle ◽

Disease Symptoms ◽

Stem Blight ◽

Gummy Stem Blight ◽

Cucumber Fruit ◽

Phoma Cucurbitacearum

In 1997, greenhouse-produced transplants of watermelon (Citrullus lanatus) developed water-soaked lesions on leaf petioles and main stems. As disease progressed, petioles and stems became necrotic and shriveled, and exuded a sticky, translucent tan liquid. Symptoms spread to leaves, which wilted and collapsed. Affected transplants eventually died. Although fruiting bodies were not observed on diseased plants, a fungal agent was consistently isolated from symptomatic tissues. When incubated under lights (12 h light/12 h dark cycle), isolates on potato dextrose agar produced numerous pycnidia with hyaline, cylindrical, one-septate conidia with mean dimensions of 5.6 × 2.8 μm. Under the same incubation conditions, isolates on V8 juice agar produced sparse ostiolate pseudothecia with bitunicate asci and hyaline, oval, one-septate ascospores with mean dimensions of 12.0 × 4.0 μm. Based on these characters, the isolates were identified as Didymella bryoniae (anamorph Phoma cucurbitacearum) (1,2). Pathogenicity was tested by producing conidial inocula of representative isolates and inoculating wounded cotyledons, true leaves, and petioles of watermelon (cv. Sangria), and wounded true leaves and petioles of cucumber (Cucumis sativus cv. Premier Hybrid) (3). Sterile, distilled water was applied to corresponding wounded tissues of control plants. All plants were kept in a humid chamber for 4 days. After 6 (watermelon) to 10 (cucumber) days, inoculated plants exhibited water-soaked lesions followed by necrosis, petiole and leaf wilting, and shriveling of tissues. Pycnidia were observed on cucumber plants after 18 days. The pathogen was reisolated from all inoculated plants and identified as D. bryoniae. Control plants developed no disease symptoms. In addition, agar plugs colonized with the watermelon isolates were placed onto cucumber fruit that were wounded slightly with a sterile scalpel. Fruit were incubated at 22 to 24°C in humid chambers and after 2 days sunken, circular lesions developed. The same pathogen was reisolated from the margins of fruit lesions. Wounded control fruit received sterile agar plugs and did not develop any symptoms. This is the first documentation of gummy stem blight on watermelon transplants in California. References: (1) W. F. Chiu and J. C. Walker. J. Agric. Res. 78:81, 1949. (2) A. P. Keinath et al. Phytopathology 85:364, 1995. (3) A. J. Wyszogrodzka et al. Euphytica 35:603, 1986.

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Outbreaks of Stem and Leaf Blight of Eustoma grandiflorum Caused by a Phomopsis sp. in Florida

Plant Disease ◽

10.1094/pdis.2000.84.4.491a ◽

2000 ◽

Vol 84 (4) ◽

pp. 491-491 ◽

Cited By ~ 3

Author(s):

R. J. McGovern ◽

T. E. Seijo ◽

B. K. Harbaugh ◽

T. S. Schubert

Keyword(s):

Agar Plate ◽

Leaf Blight ◽

Dade County ◽

Eustoma Grandiflorum ◽

Flower Production ◽

Symptomatic Tissue ◽

Stem Necrosis ◽

High And Low Temperatures ◽

Stem Lesions ◽

Fungal Suspension

Between November 1997 and May 1998, numerous lisianthus (Eustoma grandiflorum) cultivars exhibited severe stem and leaf blight at two pot-flower production sites in Hillsborough and Dade counties, FL. Blight occurred in mature plants and ranged in incidence from 3 to 5% in Dade County and from 40 to 80% in Hillsborough County. Initial stem necrosis was rapidly followed by leaf blight and production of numerous dark pycnidia in diseased tissue. As stem blight progressed, infected plants collapsed and died. Pycnidia contained biguttulate, 7.2 × 2.2-μm spores typical of Phomopsis alpha conidia; beta conidia were not observed. A Phomopsis sp. was isolated consistently when pycnidia from symptomatic stems were placed on acidified 25% potato dextrose agar after surface-disinfestation in 0.5% NaOCl; only alpha conidia were observed in culture. Pathogenicity was confirmed using a suspension of hyphae, pycnidia, and conidia made by comminuting one 95-mm-diameter acidified carnation leaf agar plate containing a 4-week-old colony of the Phomopsis sp. in 100 ml of deionized water. Six plants of lisianthus ‘Maurine Blue’ (three wounded at the crown, three nonwounded) each were inoculated with 10 ml of the fungal suspension. An equal number of noninoculated lisianthus (three wounded, three nonwounded) served as controls. After inoculation, plants were maintained in a greenhouse with average high and low temperatures of 38 and 25°C, respectively. Stem and leaf blight symptoms were observed in two of three wounded plants and in all nonwounded plants within 11 and 15 days after inoculation, respectively. Infection by a Phomopsis sp. was confirmed by reisolation from symptomatic tissue. Although this Phomopsis sp. has been detected previously in lisianthus exhibiting leaf and stem lesions (1), this report establishes the ability of the of the fungus to act as a primary pathogen and to cause extensive losses in this crop. Reference: (1) Alfieri et al. 1994. Diseases and Disorders of Plants in Florida. Bull. No. 14. Division of Plant Industry, Gainesville, FL.

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First Report of Sclerotium rolfsii on Sunflower in Italy

Plant Disease ◽

10.1094/pdis.1997.81.8.960b ◽

1997 ◽

Vol 81 (8) ◽

pp. 960-960 ◽

Cited By ~ 1

Author(s):

A. Infantino ◽

G. Di Giambattista ◽

S. Socciarelli

Keyword(s):

Crop Rotation ◽

Room Temperature ◽

Peat Soil ◽

Sclerotium Rolfsii ◽

Soil Surface ◽

Potato Dextrose Agar ◽

Soil Mixture ◽

First Report ◽

Rainy Period ◽

Stem Segments

During June 1996, 1-month-old sunflower plants (Helianthus annuus. L.) of the cvs. Blue Mix and Romsun × 590, grown at the experimental farm of the Istituto Sperimentale per la Nutrizione delle Piante (Montelibretti, Rome), showed symptoms of wilting, and then gradually dried out. Discolored areas were observed on the crown, where whitish, fan-shaped mycelia were occasionally present. A fungus was isolated on potato dextrose agar from surface-disinfested, diseased stem fragments. It also developed from diseased stem segments incubated in moist chambers. In both cases, round sclerotia developed after 9 days at room temperature. The fungus was identified as Sclerotium rolfsii Sacc. The fungus has been deposited in the ISPaVe collection (no. ER 883). To test pathogenicity, 20-day-old sunflower seedlings of the cvs. Blue Mix and Romsun × 590 were grown singly in an autoclaved peat/soil mixture in 20-cm-diameter plastic pots in a greenhouse at 30 ± 3°C. Plants were inoculated by placing five sclerotia of isolate ER 883 near the crown of each plant about 5 mm below the soil surface. For each cultivar, 10 plants were inoculated and 10 were left uninoculated. Wilting symptoms and stem discoloration appeared after 12 days. Sclerotia were produced at the stem base of some inoculated plants. All inoculated plants died after 20 days. S. rolfsii was consistently reisolated from all the inoculated plants, while no symptoms or signs were observed on the uninoculated plants. This is the first report of S. rolfsii on sunflower in Italy and has important implications for the use of sunflower in crop rotation. An unusual rainy period delayed planting of sunflowers by 1 month in 1996 and this could have favored the disease.

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First Report of Petiole Rot of Pulmonaria longifolia Caused by Sclerotium rolfsii var. delphinii

Plant Disease ◽

10.1094/pdis.2003.87.3.313b ◽

2003 ◽

Vol 87 (3) ◽

pp. 313-313 ◽

Cited By ~ 1

Author(s):

B. A. Edmunds ◽

M. L. Gleason

Keyword(s):

Sclerotium Rolfsii ◽

Soil Surface ◽

Potato Dextrose Agar ◽

Pathogenicity Test ◽

First Report ◽

Plastic Bags ◽

Affected Tissue ◽

Pathogenicity Tests ◽

The Media ◽

Herbaceous Perennial

Sclerotium rolfsii var. delphinii was isolated from the bases of discolored petioles on wilted, yellow leaves of Pulmonaria longifolia (cultivar unknown), an herbaceous perennial growing in a landscape planting in Ames, IA. White mycelia and brick red, 2- to 3-mm-diameter sclerotia were found on affected tissue and nearby soil. The isolates were identified as S. rolfsii var. delphinii based on the formation of dark red, irregularly shaped, >2.0-mm-diameter sclerotia on potato dextrose agar (PDA) around the edge of the culture (1,2). Pathogenicity tests were conducted by inoculating 5-month-old P. longifolia cv. E. B. Anderson growing in 20-cm-diameter pots in a greenhouse at 25 to 30°C. Inoculum was produced by transferring plugs from a 1-week-old culture of the S. rolfsii var. delphinii isolate on PDA to autoclaved carrot disks. After 2 days of incubation, a mycelium-infested carrot disk was placed on the soil surface at the base of each plant. Six plants were inoculated and six plants served as uninoculated controls. All plants were enclosed in plastic bags to maintain high humidity. The pathogenicity test was repeated once. All inoculated plants developed characteristic symptoms within 10 days, whereas all control plants remained symptomless. Sclerotia developed on infected tissue and the media surface, and S. rolfsii var. delphinii was reisolated on PDA from symptomatic petioles. To our knowledge, this is the first report of petiole rot of P. longifolia caused by S. rolfsii var. delphinii. References: (1) Z. K. Punja. Annu. Rev. Phytopathol. 23:97, 1985. (2) Z. K. Punja and A. Damiani. Mycologia 88(5):694, 1996.

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First Report of Chrysanthemum stem necrosis virus on Russell Prairie Gentian in Brazil

Plant Disease ◽

10.1094/pdis-06-13-0653-pdn ◽

2014 ◽

Vol 98 (2) ◽

pp. 285-285 ◽

Cited By ~ 3

Author(s):

L. M. L. Duarte ◽

M. A. V. Alexandre ◽

D. Gobatto ◽

E. W. Kitajima ◽

R. Harakava

Keyword(s):

Universal Primers ◽

Necrosis Virus ◽

Leaf Extracts ◽

Eustoma Grandiflorum ◽

Chenopodium Amaranticolor ◽

Systemic Necrosis ◽

Nucleocapsid Gene ◽

Chrysanthemum Stem Necrosis Virus ◽

Stem Necrosis ◽

Prairie Gentian

In November 2012, plants of Russell prairie gentian (Eustoma grandiflorum, Lisianthus russellianus) were collected from a commercial greenhouse in Atibaia, SP, Brazil, displaying necrotic spots on leaves and necrosis on stems, followed by generalized systemic necrosis. Disease symptom incidence was estimated at 10%. Preliminary electron microscopy observations of negatively stained leaf extracts prepared from those lesions revealed the presence of a large number of spherical tospovirus-like, approximately 100 nm in diameter. Samples of infected leaves were ground in 0.01 M phosphate buffer containing 0.5% sodium sulphide and mechanically inoculated in six plants of each species of Nicotiana glutinosa, N. tabacum cv. White Burley, N. megalosiphon, N. debneyii, Datura stramonium, Chenopodium amaranticolor, C. quinoa, and E. grandiflorum. All inoculated plants displayed local lesions 4 to 5 days after inoculation, while N. debneyii and D. stramonium showed systemic symptoms, typical of Tospovirus infection. In addition, E. grandiflorum reproduced the original symptoms. Total RNA was extracted from infected E. grandiflorum and D. stramonium, and reverse transcription (RT)-PCR was performed using universal primers BR60 and BR65 (2) targeting conserved regions of the nucleocapsid gene (N). The amplification products of approximately 450 bp were purified, cloned, and sequenced. The unknown virus was identified as Chrysanthemum stem necrosis virus (CSNV-Lis) based on host range and nucleotide sequence (Genbank Accession No. KC894721) and showed 99% identity with a CSNV chrysanthemum isolate from Japan (AB600872). Maximum likelihood phylogenetic analysis using nine homologous CSNV sequences available in GenBank classified CSNV-Lis into a monophyletic group formed by chrysanthemum isolates from Japan and China while a Japanese lisianthus isolate was separately clustered. CSNV is a member of the genus Tospovirus (Bunyaviridae) and was first reported on chrysanthemum in Brazil (1) and later in the Netherlands, Slovenia, United Kingdom, and Japan (3). Despite scattered recent reports of CSNV, the simultaneous production of chrysanthemum and lisianthus crops along the year by Brazilian farmers has contributed to the virus maintenance in the field. The high identity between Brazilian and Japanese isolates of CSNV suggest a possible reintroduction of the virus through exchange of vegetative propagating material. References: (1) L. M. L. Duarte et al. J. Phytopathol. 143:569, 1995. (2) M. Eiras et al. Fitopatol. Bras. 26:170, 2001. (3) K. Momonoi et al. J. Gen. Plant Pathol. 77:142, 2011.

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First Report of Sclerotinia sclerotiorum on Campanula carpatica and Schizanthus × wisetonensis in Italy

Plant Disease ◽

10.1094/pdis.2002.86.1.71a ◽

2002 ◽

Vol 86 (1) ◽

pp. 71-71

Author(s):

A. Garibaldi ◽

A. Minuto ◽

M. L. Gullino

Keyword(s):

United States ◽

Sclerotinia Sclerotiorum ◽

Ornamental Plants ◽

Soil Surface ◽

The United States ◽

First Report ◽

Potted Plants ◽

Initial Symptoms ◽

Stem Necrosis ◽

Campanula Carpatica

The production of potted ornamental plants is very important in the Albenga Region of northern Italy, where plants are grown for export to central and northern Europe. During fall 2000 and spring 2001, sudden wilt of tussock bellflower (Campanula carpatica Jacq.) and butterfly flower (Schizanthus × wisetonensis Hort.) was observed on potted plants in a commercial greenhouse. Initial symptoms included stem necrosis at the soil line and yellowing and tan discoloration of the lower leaves. As stem necrosis progressed, infected plants growing in a peat, bark compost, and clay mixture (70-20-10) wilted and died. Necrotic tissues were covered with whitish mycelia that produced dark, spherical (2 to 6 mm diameter) sclerotia. Sclerotinia sclerotiorum was consistently recovered from symptomatic stem pieces of both plants disinfested for 1 min in 1% NaOCl and plated on potato dextrose agar amended with streptomycin sulphate at 100 ppm. Pathogenicity of three isolates obtained from each crop was confirmed by inoculating 45- to 60-day-old C. carpatica and Schizanthus × wisetonensis plants grown in containers (14 cm diameter). Inoculum that consisted of wheat kernels infested with mycelia and sclerotia of each isolate was placed on the soil surface around the base of previously artificially wounded or nonwounded plants. Noninoculated plants served as controls. All plants were maintained outdoors where temperatures ranged between 8 and 15°C. Inoculated plants developed symptoms of leaf yellowing, followed by wilt, within 7 to 10 days, while control plants remained symptomless. White mycelia and sclerotia developed on infected tissues and S. sclerotiorum was reisolated from inoculated plants. To our knowledge, this is the first report of stem blight of C. carpatica and Schizanthus × wisetonensis caused by S. sclerotiorum in Italy. The disease was previously observed on C. carpatica in Great Britain (2) and on Schizanthus sp. in the United States (1). References: (1) D. F. Farr et al. Fungi on Plants and Plant Products in the United States. The American Phytopathological Society, St. Paul, MN, 1989. (2) J. Rees. Welsh J. Agric. 1:188, 1925.

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THE EGGPLANT BLIGHT AND FRUIT ROT IN PORTO RICO

The Journal of Agriculture of the University of Puerto Rico ◽

10.46429/jaupr.v13i2.14060 ◽

1969 ◽

Vol 13 (2) ◽

pp. 35-57

Author(s):

J. A. B. Nolla

Keyword(s):

Bordeaux Mixture ◽

Control Measure ◽

Soil Surface ◽

The United States ◽

Labor Cost ◽

Fruit Rot ◽

Seedling Blight ◽

Stem Blight ◽

Phomopsis Vexans ◽

Serious Disease

1. A serious disease of eggplants known in Porto Rico as "lunares de la hoja y tallo" and "podredumhre de la fruta", in the United States of North America as leaf blight, foot-rot, leaf-spot, stem-blight. fruit-rot, eggplant-blight and seedling-stem-blight and in Cuba as "mancha de la hoja" and "enfermedad del tallo" exists in Porto Rico. 2. All varieties of eggplant are more or less equally susceptible under Porto Rican conditions. Color of plant or of fruit has no bearing on susceptibility or resistance. 3. The disease usually brings a loss of 50 per cent or over of the crop. 4. The symptoms of the disease appear on all above-ground parts of the plant. A seedling blight, stem and petiole cankers, spots on leaf blades, fruit stalks and calices and a rotting of the young and mature fruit are produced. 5. The fungus may occur inside the seed. 6. The pathogene responsible for the malady is Phomopsis vexans (Sacc. & Sydow) Harter. 7. Variations of the fungus as have been observed elsewhere do not appear to occur in the fungus in Porto Rico. 8. The size of the pyenidiospores ranges from 5 to 8 microns in length to 1.3 to 3 microns in width. 9. The germ tube of a germinating spore may either enter through a stoma, enter through a wound or force its penetration through the cuticle. 10. Secondary cycles repeatedly occur in fields. 11. The fungus is capable of a saprophytic existence. 12. The prevailing temperature in Porto Rico seems adequate for spore germination. 13. Moisture is a very important factor in outbreaks of the disease. 14. The disease is probably controlled by a three- or four-years rotation. 15. Plants with the symptoms of the disease should be promptly removed from fields. 16. Although seed treatment is beneficial it never completely eliminates the pathogene. 17. Clean seed from unaffected fruit should be demanded. 18. Infested soils should be avoided in preparing seedbeds. 19. Inoculated soils can he rendered safe for seedlings if drenched with a 1-50 formaldehyde solution at the rate of one-half gallon per square foot of soil surface. An application of 4-4-50 Bordeaux mixture is highly beneficial but the formaldehyde treatment is to be preferred. The latter treatment will cost about two-thirds of one cent per seedling. 20. Bordeaux mixture (4-4-50) is quite effective in preventing seedling blight. The treatment is too expensive and therefore inapplicable under ordinary conditions. Bordeaux mixture may be of practical application where labor cost is reduced. The safest and cheapest control measure is to grow healthy seedlings and set them on in uninfested soils.

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