The fungus Alternaria dauci attacks the leaves of carrots above ground and can rot the vegetable below. Currently, pesticides can be used to control the fungi but are not readily available and are not a resource available to those interested in organic or sustainable methods.
Purdue University scientists, in the U.S., discovered that cultivating microbes in the soil protects carrots from the fungi when some kinds of endophytes (bacteria) work symbiotically with plant roots to decrease the chances of fungi damage.
“We found that breeding and soil health can play significant roles in the number of endophytes present and their ability to protect carrots from this devastating disease,” said Lori Hoagland, an associate professor in horticulture and landscape architecture.
Their results showed that the endophytes in the organic systems reduced growth of the damaging fungi by 44%, organic systems also had 16% more total soil matter and 43% more microbial biomass. Carrots grown in the organic system also had 50% more bacterial endophytes than those produced in the conventional systems.