Watermelon Disease Control Demonstration

Lane, Oklahoma

2008

 

Reports From Previous Trials

2004  2005   2006   2007

 

The objective of this project is to demonstrate to the use of fungicides for controlling foliar diseases in watermelon.  The demonstration will include two different fungicide treatments and two different methods that can be used to decide when to apply fungicides.

 

Fungicides: 

  1. A mixture of Dithane 75DF applied at 2 lbs. per acre and Topsin 70 WP applied at ½ lb. per acre.
  2. Bravo Weatherstick applied at 1pint per acre.

 

Application Decision Methods:

  1. Apply on a calendar schedule.  This will depend on prevailing weather. One week will be used if rainy and two weeks if conditions are dry.
  2. Apply based on the Mesonet Anthracnose Forecaster Model. 

 http://agweather.mesonet.ou.edu/models/watermelon/default.html

Fungicides are applied with a boom sprayer using 22.5 gallons of spray mixture per acre.

 

For both methods an initial fungicide application was to be made when plants began to produce male flowers.  With warm conditions plants were growing fast!  We made the first application when plants had fruit less than 2 inches long.

 

Watermelon of the cultivar Legacy was established by direct seeding on June 27 and thinned to 1 plant per 3 feet of row on July 17. 

 

Activity Record

Date

Field Observations and Activities

Fungicide Application

Calendar

Forecaster

July 31

First flowering. Make initial fungicide applications. 

 

Yes

Yes

August 12

Mesonet Anthracnose Forecaster recommends fungicide application.  Apply fungicides to the forecaster treatments.  

Foliage is mostly healthy. Some older crown leaves are tattered looking, but not diseased.

No

Yes
Aug. 14 Two weeks since the initial application.  Apply fungicides to the calendar treatments. 

Yes

No
Aug. 19 Weather has been rainy and overcast. Forecaster shows 62 hours. Eighty hours are needed before spraying is recommended.

No

No
Aug. 21 Today is the date for the calendar application to be made.  The forecaster shows 81 hours, so it should be applied also.  However, the field is too wet to spray today.  We will try tomorrow.  Foliage is free of disease so far.

?

?
Aug. 22 We sprayed the forecaster and the calendar treatments today.   The Anthracnose forecaster showed 121 hours since the last spray.

Yes

Yes
Aug. ? ?

?

?
Aug. ? ?

?

?
Aug. ?

?

?

?
Aug. ? ?

?

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For questions or comments contact Jim Shrefler by e-mail or by phone at 580-889-7343

 

This information is provided for educational purposes.  When using pesticides, always read and follow label directions.  Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by the Oklahoma Cooperative Extension Service is implied.