2022 Watermelon Update #13 – June 6

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).

Disease Update

Gummy stem blight has been by far the main widespread threat in 2022. Rains and harvesters in fields in the region will continue to provide great opportunity for spread. Inspire Super has really helped slow down gummy, but it carries a 7-day Pre-harvest Interval (PHI). Your better option for gummy stem blight control in harvesting periods is Aprovia Top, which is very comparable to Inspire Super in terms of control, yet Aprovia Top carries a 0-day PHI. (Bob Hochmuth)

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Downy mildew is present in spots throughout the region. Scout diligently for Downy mildew. The disease is referred to as wildfire as it can rapidly defoliate vines, reduce yield, and reduce fruit quality by exposing the fruit to the sun. The foliage symptoms start as small pale green or yellow spots and progress to larger brown and black blotches. Downy mildew does not affect the petioles and stems of the plant which will remain intact after defoliation. Generally, the damage affects the old growth first. If identified in your field, consider how many more harvests are planned and the pre-harvest intervals of the products you choose to spray. Orondis Ultra (preferred), or Ranman are recommended IF Downy mildew is identified in your field. Both products have a 0-day preharvest interval. (Jay Capasso)–

Powdery Mildew is still present the region but has not been widespread. Consider how many more harvests you plan in a field and choose spray options accordingly. Fields that are relatively free of diseases may not need to be sprayed as you get to your final week, but assess each field for those choices (Bob Hochmuth)

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Nutrient Management Update

Once harvests start, it is common to set the rate at 2.0 lbs per acre per day and leave it there until one week from last pick. It is not useful to fertigate that last week of harvest. (Bob Hochmuth)