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Continued<br />
from Page 16<br />
rotations in the<br />
region. Sarah<br />
Light-Area<br />
Agronomy<br />
Advisor was<br />
involved in<br />
this project<br />
in addition to<br />
the authors.<br />
We sampled<br />
soil from eight<br />
fields, five of<br />
which were<br />
confirmed to<br />
have southern<br />
blight in 2016<br />
or 2017, the<br />
other three<br />
thought to have southern blight based<br />
on grower and pest control adviser<br />
experience and observations. Six of<br />
the fields were in tomato in 2017, one<br />
was in tomato in 2016 and wheat in<br />
Figure 5: Southern blight sclerotia germination in soil samples. Note white thread-like mycelial<br />
growth.<br />
2017, and one was planted with canary<br />
bean in 2017. We sampled the soil in<br />
May 2018 to get baseline data on early<br />
season southern blight sclerotia levels.<br />
The rotational crops in 2018 included<br />
sunflower and<br />
corn. Sunflower<br />
fields were checked<br />
twice monthly for<br />
southern blight<br />
symptoms once<br />
temperatures were<br />
over 90°F for seven<br />
consecutive days<br />
because sunflower<br />
is a known host of<br />
southern blight.<br />
Tomato fields near<br />
or adjacent to the<br />
monitored fields<br />
were also checked<br />
for southern<br />
blight symptoms<br />
twice a month.<br />
Soil was collected<br />
from the same<br />
spots in the fields<br />
in August/September 2018 to determine<br />
if there were any changes to<br />
southern blight sclerotia levels in the<br />
field. Cassandra Swett’s lab analyzed<br />
the soil samples using the methanol<br />
18 Progressive Crop Consultant <strong>Nov</strong>ember / <strong>Dec</strong>ember <strong>2019</strong>