Flowering Dogwood Infections with Macrophomina phaseolina

Macrophomina phaseolina was isolated from the crown region and roots of mature flowering dogwood (Cornus florida L.) trees in the landscape and nursery plantings. Although this pathogen has been reported in Cornus species, its occurrence and impact on C. florida has not been reported. Pathogenicity tests were conducted on dogwood seedlings, and all inoculated seedlings developed root necrotic lesions and no small lateral roots, whereas the non-inoculated control seedlings remained disease-free and developed numerous small roots. Seedlings inoculated with M. phaseolina exhibited numerous microsclerotia, but non-inoculated seedlings did not. In greenhouse experiments, plants inoculated on the stems near the soil line developed brown canker-like lesions and swellings around the inoculated area. These were not observed on non-inoculated plants.

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Evaluation of Biological Agents for Control of Macrophomina Root Rot and Powdery Mildew in Flowering Dogwood (Cornus florida L.)

HortScience ◽

10.21273/hortsci13071-18 ◽

2018 ◽

Vol 53 (10) ◽

pp. 1461-1466

Author(s):

Margaret T. Mmbaga ◽

Lucas M. Mackasmiel ◽

Frank A. Mrema

Keyword(s):

Powdery Mildew ◽

Plant Growth ◽

Root Rot ◽

Plant Root ◽

Macrophomina Phaseolina ◽

Stem Length ◽

Growth Enhancement ◽

Cornus Florida ◽

Bacterial Isolates ◽

Flowering Dogwood

Six biological control agents (BCAs) (two bacteria, two fungi, and two yeasts) that were previously shown to be effective against powdery mildew (Erysiphe pulchra) were tested for efficacy against Macrophomina phaseolina root rot on flowering dogwood (Cornus florida) in the greenhouse. Two of the bacterial isolates, Stenotrophomonas sp. (B17A) and Serratia sp. (B17B), were effective in controlling both macrophomina root rot and powdery mildew, similar to fungicide control thiophanate methyl, when roots were drenched with the six BCAs individually. In addition, the two bacterial BCAs improved plant growth with respect to stem diameter, stem length, dry weight, and green foliage compared with fungicide-treated plants or nontreated controls grown in sterile soil. These results confirm previous results in which B17A and B17B suppressed powdery mildew and also promoted plant growth in flowering dogwood. Although macrophomina root rot has been previously reported as a potential problem in flowering dogwood, especially in field conditions, simultaneous infection with macrophomina root rot and powdery mildew has not been previously reported. This study confirmed that M. phaseolina infection was characterized by stubby roots and black root lesions, and plants infected with both powdery mildew and macrophomina root rot had smaller root mass compared with fungicide-treated plants. Neither of the two pathogens killed their host plants, but compounded infections significantly reduced the plant root system and plant growth. The efficacy of the two bacterial isolates in controlling both powdery mildew and macrophomina root rot suggests their potential utilization in controlling both diseases in dogwood nursery production and in other plants that are hosts to both powdery mildew and macrophomina root rot. Plant growth promoted by the two BCAs may be attributed to powdery mildew and macrophomina root rot control, but comparisons between fungicide-treated plants and control plants not inoculated with BCAs or root rot pathogen suggested that the two BCAs may play a role as bio-stimulants in growth enhancement. These results also suggest that the two biocontrol agents are not phytotoxic to dogwood.

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INOSITOL FROM BLACKBERRY (RUBUS ARGUTUS LINK) AND FLOWERING DOGWOOD (CORNUS FLORIDA)

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)84661-0 ◽

1926 ◽

Vol 68 (2) ◽

pp. 403-406 ◽

Cited By ~ 1

Author(s):

Charles E. Sando

Keyword(s):

Cornus Florida ◽

Flowering Dogwood ◽

Rubus Argutus

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SCYLLITOL FROM FLOWERING DOGWOOD (CORNUS FLORIDA)

Journal of Biological Chemistry ◽

10.1016/s0021-9258(18)84660-9 ◽

1926 ◽

Vol 68 (2) ◽

pp. 399-402

Author(s):

Raymond M. Hann ◽

Charles E. Sando

Keyword(s):

Cornus Florida ◽

Flowering Dogwood

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Dry root rot of chickpea: A disease favored by drought

Plant Disease ◽

10.1094/pdis-07-21-1410-fe ◽

2021 ◽

Author(s):

Avanish Rai ◽

Vadivelmurugan Irulappan ◽

Muthappa Senthil-Kumar

Keyword(s):

Root Rot ◽

Management Practices ◽

Lateral Roots ◽

Research Priorities ◽

Macrophomina Phaseolina ◽

Emerging Diseases ◽

Research Progress ◽

Initial Symptoms ◽

New Research ◽

The Impact

Chickpea is an essential crop for protein nutrition and is grown around the world in rain-fed conditions. However, chickpea cultivation is under threat due to emerging diseases favored by drought stress. Dry root rot (DRR), an economically devastating disease, is an example. Chickpea-specific strains of a necrotic fungal phytopathogen, Macrophomina phaseolina, cause DRR. Microsclerotia of this fungus, which are capable of withstanding harsh environmental conditions, serve as primary inoculum. Initial symptoms are scattered necrotic spots in roots, progressing to rotting and withering lateral roots, accompanied by prematurely dried, straw-colored foliage. The recent rise in global temperature and worsening of drought spells have aggravated DRR outbreaks in chickpea. To date, DRR epidemiology has not been clarified in detail. Also, the literature lacks clarity on M. phaseolina taxonomy, morphology, disease progression, and diagnosis. In this article, research progress on patterns of DRR occurrence in the field and belowground and above-ground symptoms are clarified. In addition, the current understanding of taxonomy and management practices is elaborated. We also summarize knowledge of the impact of drought and high temperature on DRR severity. Further, we provide future perspectives on the importance of host resistance, QTL identification, genotype screening for the identification of resistant genotypes. The article proposes new research priorities and a corresponding plan for the mitigation of DRR.

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