PPDL Picture of the Week
October 29, 2018
Anthracnose of tomato
Dan Egel, Clinical Engagement Associate Professor-SWPAC, Botany and Plant Pathology, Purdue University
It’s that time of year when frost has ended many a backyard
garden. Perhaps you harvested tomatoes
one last time before a predicted freeze.
These tomatoes were lined up on your kitchen counter to be added to a
fresh salad at a later date. However,
when you went to grab one of these tomatoes, you noticed a sunken area, perhaps
accompanied with an orange or salmon colored cast. What’s going on and how did this happen?
The tomato in Figure 1 has a disease known as
anthracnose. This disease is caused by a
fungus that probably splashed on the tomato before you harvested it. Although the tomato looked healthy when you
harvested it, the fungus had probably already infected the tomato. This infection expanded while the tomato sat
quietly on your kitchen counter. Before
the fungus splashed on your tomato, it probably survived on crop residue from a
tomato or pepper plant from a previous year.
If it is possible to cut the lesion out of the tomato, go ahead and add
it to your salad.
Gardeners who what to avoid anthracnose next year should do
their best not to grow tomatoes or peppers in the same area year after
year. Staking tomatoes to keep the
tomatoes off the ground should help to lessen anthracnose problems. Tomatoes mulched with plastic or straw will
have less splash of soil onto the fruit and, therefore, fewer anthracnose
symptoms. Homeowners can find out more
about controlling tomato diseases with the extension bulletin BP-184-W, Five
Steps for Healthy Garden Tomatoes found here. Commercial growers can find more information
in the Midwest Vegetable Production Guide for Commercial Growers found here.