Newly discovered pathogen in NY apples causes bitter rot disease

Date:
July 6, 2020
Source:
Cornell University
Summary:
In a study of New York state apple orchards, plant pathologists
have identified a new fungal pathogen that causes bitter rot
disease in apples.



FULL STORY ==========================================================================
In a study of New York state apple orchards, Cornell University plant pathologists have identified a new fungal pathogen that causes bitter
rot disease in apples. In addition, a second related fungus known to
cause rot disease in other fruits was found for the first time in apples.


==========================================================================
"We were shocked by what we found, just dumbfounded," said Srdjan
Acimovic, a senior extension associate at the Hudson Valley Research
Laboratory (part of Cornell AgriTech) and the paper's senior author. "We
found these two species, one that has never been described before and one
that has been described before but never on this host." Both pathogens
belong to the genus Colletotrichum, which contains 189 species of fungi
that cause devastating rot diseases in a wide variety of fruit crops,
including banana, strawberry, citrus, avocado, papaya, mango and apple.

If protective practices are not applied in a timely manner, apple losses
from bitter rot in New York state can average up to 25% per year, with
reports of some organic farms losing up to 100% of their crop. Bitter
rot also accounts for up to 5% additional loss of marketable fruit in
storage post-harvest.

This damage is costly for farmers; the farm gate value for New York
apples was roughly $260 million in 2018, according to U.S. Department
of Agriculture statistics.

The dominant species found in the apples was C. fioriniae, followed by C.

chrysophilum, which is found in other fruits but not apples until now,
and the newly discovered C. noveboracense, named after New York state
in Latin.

Colletotrichum fungi that infect apple fruit can largely be divided in
two main groups. One group called the C. gloeosporioides complex thrives
in warmer growing regions than the other group, the C. acutatum complex,
which is more frequently reported in cooler apple growing regions. And
based on the group they belong to, species can react differently
to fungicides, which the researchers also tested. For this reason,
identifying and characterizing the fungi is important for bitter rot management.

"When we know which species are dominant in our area, we know how
environmental conditions will affect them and which control method
is best in an orchard," said study first author Fatemeh Khodadadi,
a postdoctoral researcher in Acimovic's lab.

In the future, the researchers plan to work with other plant pathologists
and apple breeders to identify possible genes that confer natural
resistance to Colletotrichum fungi that may be bred into apple cultivars.


========================================================================== Story Source: Materials provided by Cornell_University. Original written
by Krishna Ramanujan. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Fatemeh Khodadadi, Jonathan B. Gonza'lez, Phillip L. Martin, Emily
Giroux, Guillaume J. Bilodeau, Kari A. Peter, Vinson
P. Doyle, Srđan G. Aćimović. Identification and
characterization of Colletotrichum species causing apple bitter rot
in New York and description of C. noveboracense sp. nov.. Scientific
Reports, 2020; 10 (1) DOI: 10.1038/s41598-020-66761-9 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200706145435.htm

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