Temperature relations of powdery mildews

Yarwood, C. E.; Sidky, S.; Cohen, Menashe; Santilli, Valter

doi:10.3733/hilg.v22n17p603

Cited by 34 publications

(20 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The variation in peak mean PDI values may also indicate possible existence and role of physiological races of cucurbit powdery mildew pathogen or may be attributed to extreme dryness under irrigated conditions. These findings are in conformity with those of Yarwood [28], who reported role of physiological races in case of powdery mildews of different crops and the decline in powdery mildew prevalence with increase in rainfall and decline in sporulation of the powdery mildew fungi with increase in temperature above the optimum of around 21 o c. These results further indicate dependence of disease intensity on factors like cultural practices. For example, higher PDI range (33.34% to 96.66%) was registered under sprinkler irrigation conditions compared to the range of 23.34% to 78.34% under rain fed conditions.…”

Section: Effect Of Pumpkin Accession On Peak Powdery Mildew Severity supporting

confidence: 80%

Slow mildewing in Pumpkins: an opportunity to reduce Pumpkin yield losses caused by Erysiphe cichoracearum

Chilasa

Saka²,

Bokosi³

et al. 2016

IJBAS

View full text Add to dashboard Cite

Pumpkin powdery mildews, a disease caused by fungus Erysiphe cichoracearum, is one of the major diseases that reduce yield and quality of pumpkins. A field screening study involving fifty two pumpkin accessions was carried out at three powdery mildew hot spot sites in Malawi. The main objective was to assess the reactions of pumpkin accessions to E. cichoracearum. The experiment was laid out in a randomized complete block design replicated three times. Plot size was 3m x 3. 7m. There were statistically significant differences in apparent infection rates (P<0.001), area under disease progress curve, AUDPC (P<0.001), percent disease index, PDI (P<0.001) among the accessions across all sites. Pumpkin accessions 6 and 42 consistently showed slow rate of powdery mildew development at 4 th , 6 th , and 8 th week after germination. A strong positive correlation (R= 0.7 at 8 th week, and 0.97 at 12 th week after germination) was observed between the number of rotten fruits and AUDPC. This study showed that out of the fifty two pumpkin accessions tested, none was immune to Erysiphe cichoracearum. However the accessions that recorded very slow rate of powdery mildew development showed high potential to maintain viable vines and support their fruits up to physiological maturity. We concluded that promoting slow mildewing pumpkin genotypes is appropriate solution to fruit yield and quality losses caused by E. cichoracearum.

show abstract

Section: Effect Of Pumpkin Accession On Peak Powdery Mildew Severity supporting

confidence: 80%

Slow mildewing in Pumpkins: an opportunity to reduce Pumpkin yield losses caused by Erysiphe cichoracearum

Chilasa

Saka²,

Bokosi³

et al. 2016

IJBAS

View full text Add to dashboard Cite

show abstract

“…The response of germination of fungal spores to temperature is known to be affected by a variety of factors, such as the time of observation (Felton and Walker 1946), the pH of the medium (Tilford 1936), and the nutrient supply (Yarwood et al 1954). Thus the appearance in the literature of differing optimal temperature ranges for the germination of P. tabacina conidia is hardly surprising.…”

Section: (B) Effect Of Physical Factors On Germination and Germ-tube mentioning

confidence: 94%

Germination of Conidia of Peronospora Tabacina Adam I. Germination in Vitro

Shepherd¹

1962

Aust. Jnl. Of Bio. Sci.

View full text Add to dashboard Cite

SummaryWashed conidia of Perono8pora tabacina Adam germinated poorly or not at all in water alone, but germinated in the presence of riboflavin. The rate of germination of conidia in liquid suspension was enhanced by the presence of carbon and nitrogen sources, phosphate, and calcium and magnesium ions. The effects of 141 metabolites on germination and germ-tube elongation have been tested.A number of analogues of natural metabolites were inhibitory to germination and germ-tube elongation. Extracts and exudates of tobacco leaves did not affect either the amount or rate of germination.Washing by centrifugation increased the percentage of conidia that germinated subsequently and the presence of a germination inhibitor in unwashed conidia is postulated.The optimum temperature for germination of conidia on agar, or in liquid suspension, was in the range 15-20°C. The pH optimum varied with the constitution of the medium; when germinated on 2 % agar a broad optimum was shown at pH's 5·5-8·0, whereas in liquid suspension the optimum was in the pH range 6· 5-8· O.When conidia were tested within 24 hI' from the time of initiation of sporulation, germination was high (85%). After 48 and 72 hI' germination had dropped to 61 and 48% respectively.Washed spores showed no loss of germination capacity when kept for up to 6· 5 hI', but germination was negligible after 18 hr storage.Visible light did not affect germination, but 9000 fLWfcm2 of ultraviolet light reduced it to 2·7%.

show abstract

“…For example, the genomes of warm-blooded vertebrates have higher G+C contents than those of cool-blooded vertebrates (Salinas et al, 1988). The optimum temperature for growth is 1 5-20~ in B. gram/n/s, which is lower than those of the d/cots-parasitic powdery mildews, 20-30~ (Yarwood et al, 1954;Lenkyn and Bainbridge, 1978). The relatively low G+C content of B. grarninis might reflect the low optimum temperature of the fungus.…”

Section: G -T-c Contents and Nucleotide Length Of Rdna Its Regionsmentioning

confidence: 99%

Phylogenetic analysis and predicted secondary structures of the rDNA internal transcribed spacers of the powdery mildew fungi (Erysiphaceae)

Takamatsu¹,

Hirata²,

Sato³

1998

Mycoscience

View full text Add to dashboard Cite

The nucleotide sequences of the internal transcribed spacer (ITS) regions of the ribosomal DNA including the 5.8S rRNA gene and the 5' end of the 28S rRNA gene have been determined for 19 species in 10 genera of the powdery mildew fungi in order to analyze their phylogenetic relationship. These fungi were divided into two large groups based on the nucleotide length of the ITS regions, and this grouping was in line with that based on the morphological characters of the anamorphic stage rather than the teleomorphic stage. Although the variable ITS sequences were often ambiguously aligned, conserved sites were also found. Thus, a neighbor-joining tree was constructed using the nucleotide sequence data of the conserved sites of the ITS regions, the 5.8S rRNA gene, and the 5" end of the 28S rRNA gene. The phylogenetic tree displayed the presence of four groups in the powdery mildews, which were distinguished by their morphology and/or host ranges, in the ITS2 region, the presence of a common secondary structure having four hairpin domains was suggested, in spite of the highly variable nucleotide sequences of this region. The predicted secondary structure was supported by the compensatory mutations as well as compensatory conserved sequences and high G-t-C content in the predicted stem regions.

show abstract

Temperature relations of powdery mildews

Cited by 34 publications

References 11 publications

Slow mildewing in Pumpkins: an opportunity to reduce Pumpkin yield losses caused by Erysiphe cichoracearum

Slow mildewing in Pumpkins: an opportunity to reduce Pumpkin yield losses caused by Erysiphe cichoracearum

Germination of Conidia of Peronospora Tabacina Adam I. Germination in Vitro

Phylogenetic analysis and predicted secondary structures of the rDNA internal transcribed spacers of the powdery mildew fungi (Erysiphaceae)

Contact Info

Product

Resources

About