Avoid Resistance and Disease With Prevention Plan

All growers can imagine the perfect settings needed to produce their best yield. Unfortunately, for many growers, that ideal situation isn’t always possible. Whether it’s to prepare for unexpected weather or to determine the right time to apply chemicals, establishing a solid weed management and disease prevention plan is vital for all growers’ success.

Rotating Chemistries

To keep diseases guessing, growers should rotate chemistries in different FRAC groups for resistance management. According to BASF, it takes around 10 years for a new fungicide to be developed; so practicing excellent product stewardship and using fungicides at their full labeled use rate is essential to ensure the longevity of formulas.

“Growers know the importance of product stewardship through rotating fungicides with different FRAC codes,” said Leigh Ann Harrison, Technical Service Representative for BASF. “They rely on these chemistries to protect their yield and want to be able to keep using them for many more seasons.”

Knowing what chemicals to use on your plants can be determined by working with your PCA. The best time to discuss this plan is during dormancy.

When to Spray

“Fungicides are most effective when used preventatively, before disease outbreaks occur,” Harrison said. “Most seasons’ applications begin at bud break with microionized sulfur and continue with sulfur or fungicides on 7- to 14-day intervals, depending on the conditions.”

Another important time to apply a powerful and effective chemistry is right before bunch closure. By applying at this time, growers can protect the health of the crop and the yield quality. This is typically the time when Botrytis bunch rot begins to appear, so applying a chemistry that not only prevents Botrytis bunch rot, but also powdery mildew is a great way to fight off multiple diseases at once.
To monitor a disease or determine when a fungicide should be applied to your field, Harrison suggests using the UC-Davis powdery mildew risk index. This website provides growers with explanations on when and what to use to protect their fields.

Avoiding Resistance

“When you have a strong fungicide program, [spraying] every 7 to 10 days with good rotation, you see a reduction in inoculant and your probability of seeing resistance is reduced,” said Hector Mariscal, an independent Pest Control Advisor at DEVAN, Inc. “The challenge is to mix chemistries and classes so we don’t get resistance and can use the tools that we have at our disposal to make a long season uneventful.”

According to Max Jehle, a Pest Control Advisor at MAX Agriculture Consultants Inc., many cases of resistance are actually signs of sprayer issues. “When you do see ‘resistance’ to a material, especially in a heavy pressure season, you should check your sprayer to see if you are applying it correctly,” said Jehle. “Many resistance problems are normally an application error that reduced the coverage of the material.”

Finding Your Formula

“You can’t cover every leaf in the canopy 100%,” said Chris Cucuk, a Pest Controls Advisor at Cucuk Consulting in California. “That’s why it is important to go in with dusting sulfur between applications and to use a systemic fungicide such as Pristine fungicide.”

The local systemicity of Pristine® fungicide ensures that parts of the plant that did not receive direct treatment still have protection from diseases.


Product stewardship begins long before the first signs of fungal growth. To learn more about product stewardship and resistance management, visit www.GrowSmartGrapes.com.


Always read and follow label directions. Pristine is a registered trademark of BASF. © 2017 BASF Corporation. All rights reserved. APN #17-SPC-0005.