2022 Watermelon Update #7 – April 25

Bob Hochmuth with input from Suwannee Valley Extension Agents: Mark Warren (Levy), Tyler Pittman (Gilchrist), Tatiana Sanchez (Alachua), Luke Harlow (Union), Jay Capasso (Columbia), Dan Fenneman (Madison), Keith Wynn (Hamilton), Danielle Sprague (Jefferson), Emily Beach (Lafayette), Amanda Phillips (Suwannee), Kevin Athearn (RSA-Agri- business), and Sudeep Sidhu (RSA- Water Resources).

 

First Powdery Mildew Confirmation of 2022 

We had the first UF lab confirmation of powdery mildew in the Suwannee Valley this past week. The sample collected did not show vivid symptoms of powdery mildew, however, the UF Plant Diagnostic lab at UF found powdery mildew. So, we now know the conditions are favorable for powdery mildew and it simply “feels like” powdery mildew weather now, dry breeze, and relatively low humidity. As a result, we suggest you start your powdery mildew preventative fungicide programs. Once powdery mildew is present, we recommend you rotate between Quintec and Procure. This weekly rotation worked well last year when started early. Research results last year in the Suwannee Valley showed these two materials were still effective and showed low resistance levels. Switch may be another option later in the season, but we suggest you start with Quintec and Procure rotated and one or the other sprayed weekly along with your broad-spectrum fungicides (Mancozeb or Chlorothalonil). Intensify your scouting regimen now until harvest. (Mark Warren, Bob Hochmuth)

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Fusarium Wilt 

We are continuing to see Fusarium Wilt in some fields as plants get to the point of vigorous fines and fruit set. Wilt becomes evident as the vigorous vines demand more water than the plant can get through its Fusarium clogged vessels. The warm weather should help slow the spread of the disease but expect to continue to see more plants succumb to Fusarium. We wish there was a magic bullet at this stage of the season, but there is none. Proline has to be applied very early in the season to be effective. I caution growers to think hard before spending a lot of money on expensive cocktails as a remedy. I saw some of these firsthand in 2021 with absolutely no effect on the level of control. Believe me, we wish we had a silver bullet for you on this one. (Bob Hochmuth, Mathews Paret, and Tatiana Sanchez)

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Petiole Sap Testing Results 

 Extension Agents in the Suwannee Valley are now in full swing with petiole-sap testing for nitrogen and potassium. Collectively Extension Agents and support staff are sampling over 100 fields each week now. Prior to last week, most samples were high on N and perfect on K. Sampling during the end of last week began to show significant movement on nitrogen in fields where many baseball or larger-sized fruit were seen. In these fields, potassium was still excellent, but nitrogen began to naturally decline. In those fields, it was common to recommend increasing fertigations to 2.0 lbs. per acre per day rates of nitrogen and potash. This is only informational and not intended as an across-the-board recommendation for everyone. Use the guidance given by Extension Agents in YOUR fields. With very high prices of nutrients, this is not the year to over fertilize! (Bob Hochmuth and Mark Warren)