by Layne Wade, Technical Service Manager, Arysta LifeScience

Although it is harvest time, when it comes to grape growing, there is no off-season. What happens in your vineyard right now has the potential to affect next year’s season as well. Follow these simple “do’s and don’ts” for a strong finish this season and a strong start on the next.

Do’s

The mode of action (MOA) you are using can be the difference between a healthy vineyard and a Botrytis outbreak. Alternating modes of action helps prevent pathogen populations from developing resistance to classes of fungicides. It is important to think about the classes of fungicides available when building your resistance management plan for the season. These classes have different modes of action and will each affect the fungus differently. Arysta LifeScience recommends a diseases management program that rotates fungicides with different modes of action for the most effective method of resistance.

Harvest is a good time for growers to reflect on the season’s disease management program and evaluate the effectiveness of it. Wise grape growers will note when their vineyard experienced disease, the level of severity and what products were applied. Taking notes during this process will help plan for next year’s disease management program.

Don’ts

It is often forgotten that Botrytis is a threat during all seasons. Grape growers should continue walking through their vineyards scouting for any sign of disease because there’s a chance infection may still be actively occurring. Late-season Botrytis infections are most severe when relative humidity exceeds 92 percent, free moisture is present on the fruit surface and temperatures are in the 58 to 82 °F range, according to UC IPM. Ripe berries that have experienced damage from insects, birds, hail or machinery are even more susceptible to disease, as the juice in the berry can provide the necessary water and nutrients for fungal growth. This makes September a critical month for scouting.

It's no secret how devastating Botrytis bunch rot can be to grape yields, which is why it’s important to stop Botrytis in its tracks to avoid overwintering. Botrytis cinerea, the causal agent of bunch rot, overwinters as sclerotia, which are hard, resistant structures sometimes referred to as "berry mummies." Following rain or irrigation, sclerotia germinate and produce spores that travel via air currents or rain showers. Grape growers use fungicides like PH-D and ELEVATE  to protect current fruit and minimize the potential future effects of overwintering Botrytis bunch rot and give grapevines a solid foundation leading into the next growing season.

As the sole member of the FRAC group 17 fungicide class, ELEVATE® Fungicide is an excellent addition to your resistance management plan. This product is a protectant fungicide that binds with the waxy layer of the grape and disrupts the Botrytis life cycle from spore germination to the beginning of mycelial growth and colonization. When used in a tank mix or rotation with other fungicides, it delivers dependable and economical control from first bloom all the way to harvest. It has no impact on most beneficial insects and features a unique active ingredient, fenhexamid, with no known cross-resistance to other commonly used fungicides.

Another tool trusted for Botrytis control is PH-D® Fungicide. PH-D is a strong choice for prevention of Bunch rot caused by Botrytis and other secondary rot-forming fungi such as Cladosporium. PH-D is a FRAC Group 19 fungicide with a 0-day pre-harvest in grapes and features a unique mode of action (MOA), making it an ideal addition to a rotational management program to aid in resistance management.

PH-D does double duty, because it is also used for quick knockdown of Powdery mildew. Brett Ploszaj and Kevin Hodges of Crop Production Services, recently renamed Nutrien Ag Solutions, praised PH-D for control of that hard-to-get-rid-of Powdery mildew that growers may experience in the months prior to harvest.

“PH-D gave a 75–80 percent reduction in the Powdery mildew. Hands down the best Powdery mildew knock-back I have ever seen,” said Ploszaj of Madera, California. 

Kevin Hodges of Fresno, California, agreed. “PH-D did a good job of knocking the Powdery mildew back. The Powdery mildew did come back in the heaviest spot, but 95 percent of the block was cleaned up with the PH-D,” he said.

No matter the disease pressure, you can count on Arysta LifeScience for a complete line of grape protection and a staff dedicated to keeping your vineyard going strong. Contact your retailer or Arysta LifeScience sales representative for additional information, or visit www.arysta-na.com.

_{Always read and follow label directions. ELEVATE and PH-D are registered trademarks of an Arysta LifeScience Group Company. Arysta LifeScience and the Arysta LifeScience logo are registered trademarks of Arysta LifeScience Corporation. © 2018 Arysta LifeScience Group Company. SPC-17108}