Mar 15, 2019

Battling powdery mildew and Botrytis with Pristine fungicide

{Sponsored} Last season, powdery mildew pressure was very late for coastal grape growers in California. Not knowing when diseases will develop or how severe pressure will be, growers need to prepare and be proactive.

In 2018, coastal grape growers experienced a warm February, a cool and wet March, and then a warm, dry summer that led to some changes in the grape growing cycle. “We saw a split bloom in some regions and varieties. We also had an early bloom followed by cool weather, resulting in slowed development. When the weather warmed up again, there was a second bloom flush,” said Kate Walker, BASF Technical Service Representative. “This made Botrytis management

decisions more difficult for growers with the presence of both flowers and berries.” Since 2017 saw high disease pressure, growers were proactive in the application of chemistries to prevent both powdery mildew and Botrytis.

Walker recommends that growers do not become complacent; a strong program for both powdery mildew and Botrytis will help growers now and in future seasons. For a product that controls both diseases, Walker recommends Pristine® fungicide. Pristine fungicide works by stopping energy production in the cells of pathogenic fungi.

In addition to providing control of the two diseases, Pristine fungicide also provides Plant Health benefits to grape crops, such as increasing photosynthesis and the rate of sugar accumulation for earlier harvest potential.

Seeing application success

Growers need to consider tank-mix options available to them as well as sulfur and oils as a complement to Pristine fungicide. When used with other FRAC groups outside of groups 7 and 11, such as Vivando® fungicide, Pristine fungicide is “a great rotational partner,” said Walker. “When you make 8 to 10 applications in a season, you need to rotate your chemistries and not use the same mode of action for two applications in a row.”

When applying, Walker recommends growers follow these rules of thumb for best results:

1. Pristine fungicide can be applied at any time for powdery mildew; however, the optimal time for growers to apply Pristine fungicide is during the bloom stage in May or June.

2. Rather than making too many applications, growers should target the applications to recommended spray timings.

3. Start early with fungicide applications and keep the interval tight at the beginning of the season. It is easier to reduce the number of applications or adjust the application interval if disease pressure is lower during the season than to add additional applications to try to control existing powdery mildew or Botrytis infections. In other words, starting with a strong program and selecting the right materials will allow for more flexibility during the growing season.

4. Vivando fungicide should be used early in the season as part of a grower’s disease protection rotation.

5. In order to optimize the effectiveness of these chemistries, Walker recommends that growers pull leaves to increase airflow in the canopy. “Where there is humidity or freestanding moisture, powdery mildew will thrive,” said Walker.

6. In addition to rotating chemistries such as Pristine fungicide and Vivando fungicide, growers should also use sulfur for additional powdery mildew control and resistance management.

Keeping a strong front in the battle against powdery mildew and Botrytis is important for preserving the yield and quality of a grape crop. By utilizing the right chemistries at the correct time, growers will see lower disease pressure now and in future growing seasons. For more information on how Pristine fungicide and Vivando fungicide can protect your grape crop, contact your local BASF representative.

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