Peninsula Enterprise

In order to prevent black rot infection of grapes, the number, time of application, materials to use, and the purpose of the spray are recommended as follows:

1. Dormant season—Lime-sulphur, 32 deg. Baume, diluted 1 to 8 for scale and general clean-up.

2. When second or third leaf shows—Bordeaux 4-5-50. Add 1/2 pound resin or fish oil soap or 1 pound soybean flour for Anthracnose, bitter rot, black rot, mildew.

3. Before blossoms open—Same as No. 2 for the same purpose.

4. After blossoms fall—Same as No. 2 for the same purpose.

5. Ten to fourteen days later—Same as No. 2 for the same purpose.

Then at 2-week intervals until within two weeks of harvest time—Same as No. 2 for the same purpose.

Lead arsenate, 2 pounds powder to each 50 gallons of solution, should be combined with Bordeaux if chewing insects make an appearance.

Burgundy mixture may be substituted for Bordeaux in the last spray in order to prevent discoloring of the fruit. The following formula is suggested: Sodium carbonate (Sal soda)—1 1/2 pounds; Copper sulphate—1 pound; Water—50 gallons; Soybean flour—1/2 pound. Prepare and apply same as Bordeaux.

Successful control will depend upon strict adherence to this schedule, together with thorough application of the materials recommended. It must also be remembered that the first four sprays are the most important and must be applied as recommended in order to secure control.

Infection takes place early in the season and as Bordeaux mixture is a preventive and not a cure, application must be made before the spores of the black rot fungus begin to germinate.