Subscribe Now Subscribe Today
Science Alert
 
FOLLOW US:     Facebook     Twitter
Blue
   
Curve Top
Plant Pathology Journal
  Year: 2016 | Volume: 15 | Issue: 3 | Page No.: 108-123
DOI: 10.3923/ppj.2016.108.123
Maturation, Ascospores Discharge Pattern and Relevance of Mills Criteria for Predicting Apple Scab Infection Period in India
K.P. Singh, J. Kumar, A. Singh, R.K. Prasad, R.P. Singh and D. Prasad

Abstract:
Background: Apple scab, caused by Venturia inaequalis (Cke.) Wint. (anamorph Spilocaea pomi Fr.) is considered to be one of the most important fungal diseases of apple. In Uttarakhand Himalayas, the yield losses during scab epidemic years in 1996 and 2008 went up to 70%. Methodology: Random surveys were conducted during 1995-2014 from 3rd week of August until last week of September in apple orchards planted mostly to cv., Delicious. An apple scab forecasting and monitoring systems (μMETOS, Austria) installed at overwintering sites at Bhatwari fruit belt, Purola-Naugao, Tuni-Chakarata and Auli-Joshimath fruit belts recorded weather parameters including temperature, which were used to calculate degree-day accumulations. Results: The leaves falling early in the season appeared not to contribute much to the build-up of primary inoculum for the ensuing apple season. Leaves falling late had more scab lesions per leaf and posed a greater risk of increasing primary inoculums. The pseudothecia formation took 32-48 days more after sexual reproduction at temperature around 8-10̊C and this process was completed between February and March every year. The maximum ascospore productivity was recorded at fruit development stage of apple with ascospore productivity of 1,23,000 mL–1, which declined gradually. The ascospore emission period was 64-78 days and mean number of cumulative degree-days for 50 and 95% spore release were 456 and 960, respectively. Mills infection periods ranging from 19-47 were recorded from April-September every year that varied depending upon the weather conditions. The results revealed 2 day (light infection), 1 day (moderate infection) and 1 day (severe infection) delay in symptom expression under orchard conditions. Wetting requirement for infection to occur was also found to be more. More wetting of the leaves was required and symptoms were expressed within 7-9 days at higher temperature. Conclusion: The results of this study provide evidence that the use of average daily temperatures in spring to developed forecasting models based on degree-day accumulation could be used to predict the beginning and the end of the ascospore discharge during the apple growing season. The reduction of primary inoculum sources could have a decisive role in the management of apple scab.
PDF Fulltext XML References Citation Report Citation
 RELATED ARTICLES:
  •    Predicting Potential Ascospore Dose of Venturia inaequalis (Cks) Wint in Farmers Apple Orchards in Central Himalayas of India
How to cite this article:

K.P. Singh, J. Kumar, A. Singh, R.K. Prasad, R.P. Singh and D. Prasad, 2016. Maturation, Ascospores Discharge Pattern and Relevance of Mills Criteria for Predicting Apple Scab Infection Period in India. Plant Pathology Journal, 15: 108-123.

DOI: 10.3923/ppj.2016.108.123

URL: https://scialert.net/abstract/?doi=ppj.2016.108.123

 
COMMENT ON THIS PAPER
 
 
 

 

 
 
 
 
 
 
 
 
 

 
 
 
 
 
 
 
 
 

       

       

Curve Bottom