Warmer Temps Increase Chickpea Diseases

NEW DELHI - May 31/10 - SNS -- Periods of prolonged heat during the growing season seem to be increasing the susceptibility of chickpeas to new diseases, report researchers at the International Crops Research Institute for the Semi-Arid Tropics (ICRISAT).

Recent studies by ICRISAT in India indicated that drought caused by prolonged high temperatures increase the vulnerability of chickpea (channa in Hindi) to dry root rot caused by a fungus known as Rhizoctonia bataticola. Dry root rot is one of the two diseases that affect chickpea production; the other is Fusarium wilt.

Commending the findings, Director General of ICRISAT, Dr William Dar said, "The revelation fortifies ICRISAT's stand that climate change has far reaching impact on food security and the lives of the poorest of the poor. It also reminds us of our responsibility to further study the behavior of pathogens at different levels of temperature and soil moisture."

Chickpea is a major food legume grown mostly by the poor and subsistence farmers in the semi-arid tropics of Asia and Africa. The studies indicated that under the emerging climate change, high temperature and the resultant rapid soil moisture deficit at reproductive growth stages predisposes chickpea to outbreaks of dry root rot.

There are substantial sources of resistance to Fusarium wilt for chickpea, but none against dry root rot, but dry root rot symptoms can easily be mistaken for Fusarium wilt. The confusion leads to questions about why Fusarium wilt resistant chickpeas are dying? Is Fusarium wilt resistance breaking? And whether a new disease has emerged?

Studying data from 2005 to 2010 during the post-rainy season in India, scientists found that there is higher incidence of dry root rot in Fusarium wilt resistant chickpeas in the years when temperatures are over 33 degrees Celcius.

Research under different soil moisture and temperature levels revealed that the pathogen infected chickpea plants and manifested dry root rot faster at 35C with soil moisture levels less than or equal to 60%. Fusarium wilt occurs at temperature 25C and soil moisture levels more than 60%.

ICRISAT's studies clearly demonstrate the combined role of drought plus pathogen (Rhizoctonia bataticola) responsible for dry root rot infection and development.