After southern blight showed up in several tomato fields in the Sacramento Valley, researchers began work to quantify the spread and impact of the disease in annual rotations in the region. The research team sampled soil from a total of nine fields, five of which were confirmed to previously have southern blight.
“In 2017 with those really heavy rains and all the late plantings with tomatoes, it created a lot of problems for processing tomatoes and southern blight kind of showed up in a lot of places and it’s generally not an issue up here,” said Area Vegetable Crops Advisor for Colusa, Sutter and Yuba Counties, Amber Vinchesi-Vahl. “Their fields that were affected, those growers are very concerned because southern blight can be very devastating.”
Southern blight symptoms did not appear to show up in 2018 in the fields that were being monitored, but sclerotia was found in fields where sunflower crops were being grown in rotation. “With corn it was kind of a mix,” Vinchesi-Vahl noted. “So, we would recommend that over sunflower, if you do have southern blight in your fields, as a rotational crop because it is less likely to increase the amount of disease in the soil.”