Clemson Extension Agents Provide Crop Updates

Jim Rogers South Carolina

Weekly Field Update

Clemson Extension agents provide updates in The South Carolina Grower this week about the status of various crops being produced throughout the state.

South Carolina Grower

Statewide

Justin Ballew reports, “The coldest temperature I heard of right before Christmas was 7 degrees (in the upstate). That is certainly low enough to damage strawberry crowns. While most folks had their fields covered, we have seen a little crown damage in parts of the field where the row covers didn’t reach all the way to the end of the row or where there was a tear in the covers. This is apparent by a light brown discoloration in the crown that is visible when the crown is cut open. Since this damage occurred a couple weeks ago, these plants are pretty easy to pick out, as they haven’t put out any new growth. Unfortunately, Neopestalotiopsis has been confirmed on numerous strawberry farms around the state. We’ve seen it on Ruby June, Camarosa and San Andreas. It shows up first as a leaf spot and can show up in the crown, and later in the season on the fruit. There are some other fungal diseases that create a similar foliar symptom (Phomopsis, Gnomonia, etc.). If you see large leaf spots, submit samples to the Plant and Pest Lab for diagnosis right away. Guido Schnabel is recommending strict sanitation of the infected leaves, on dry days only (burn or bury the leaves), and applications of Thiram and Switch (apply Switch prior to rain events) to manage the disease ahead of bloom, if it is confirmed in your field by the lab.”

Coastal Region

Rob Last reports, “What a difference a couple of weeks can make, going from a hard freeze event before Christmas to much more mild and temperate conditions. Given the extent of the Christmas cold, crops are showing damage to leaves and stems. If you haven’t already done so, sanitation will be critical. Removing dead and damaged strawberry leaves will help to reduce sources of inoculum for later in the season (think gray mold). I am getting a lot of questions regarding the yield impacts of the cold; it may be too early to truly tell. Delaying pruning on crops, such as peaches, may be beneficial to see any damage to flower buds. One note of caution is that as temperatures are much warmer, crops may be triggered into spring growth, increasing the potential for damage from a later cold event. Planning now will be very beneficial. Scouting and crop monitoring will be vital as we go forward.”

Zack Snipes reports, “I hate to start the first report of the year with bad news, but we have found and confirmed Neopestalotiopsis in strawberry throughout SC, including the Lowcountry. This is a new disease that growers, Extension agents, and specialists found in Florida a few years back. This disease can be very aggressive and take down entire plants very quickly. Right now, sanitation and an aggressive spray program is how we are fighting it. I am finding this disease on Ruby June plants initially, but also seeing it some in Camarosa. The symptoms look like a “bullseye” on the leaf margins. The bullseye area will be brown/tan, and the edge of the symptoms will be a purple color. The signs of the disease are tiny black dots which are the reproductive structures of the fungus. Do not confuse this disease with cold damage. If you haven’t looked at your strawberries in a while, please scout them ASAP and call your local agent as quick diagnosis and treatment are critical to having berries to sell this year.”

Midlands

Phillip Carnley reports, “Orangeburg and Calhoun counties came through the cold of December alright for the most part. In our leafy greens, there is some cold damage, especially in cabbage on the older skirt leaves but the heads seem to have made it through just fine. Our biggest issue by far is the emergence of Neopestalotiopsis. This disease has a few characteristics to look for that distinguish it from other crown diseases of strawberries. Usually, there are leaf lesions that will have concentric rings and with a white or tan center with black acervuli in the center. When present on infected fruit it can resemble anthracnose. Control options are very limited at the moment with Thiram and Switch being the most effective at slowing down the progression of the infection. Sanitation is key and all crown material should be removed from the field if possible as to not harbor the pathogen. In my area it does seem to favor more wet conditions so the dryer the site the less vigorous it seems to spread. If you suspect an infection, please contact your local agent to sample for this new disease.”