In the cycle of vineyard management, every season brings its unique set of challenges and opportunities. As we navigate past fruit set but not quite at veraison, our focus should pivot to protecting and enhancing the quality of the fruit that is already on the vines. This period demands precise interventions to ensure the health and quality of our crops. Below are six key areas of vineyard management that can easily go awry in this midsummer season, as well as how to avoid those mistakes in your vineyard.
- Improper Canopy Management
An essential element of maintaining vine health and fruit quality involves managing the canopy efficiently. Overexposure to sunlight, especially in warm or hot climates, can risk the integrity of the fruit. Controlled leaf removal in the fruit zone can mitigate this, but timing is critical. Perform this task just after fruit set to allow grapes the opportunity to adjust to the sun’s intensity. Additionally, hedging should maintain a shoot size of 3-5 feet to adequately ripen most grape varieties, with careful attention not to create a “taco canopy,” which shades and weakens the lower canopy.
- Navigating Summer Sprays Cautiously
Summer sprays pose a tricky challenge with their pre-harvest intervals. Applying sulfur or oils during high temperatures can damage both fruit and canopy, escalating the risk of burns. And a grower should never mix sulfur with oil in a tank, even if temperatures are cool. A strategic shift to alternative powdery mildew products less sensitive to heat can help you navigate through the hotter months, ensuring your vines remain protected without the potential of being burned.
- Late Crop Adjustments
Adjustments to your crop should ideally be done by shoot thinning, but the ideal time to drop fruit is at or just after lag phase. Once the berries enter the lag phase and the cells stop dividing, growth stalls, and then berries enlarge due to cell enlargement. Dropping fruit at or after lag phase can help to improve the ripening of the remaining crop, without causing issues with berry size compensation, which can increase risk of bunch rots.
- Adding Fertilizer Too Late in the Year
Adding fertilizer, particularly nitrogen, too late in the season can spur unwanted vegetative growth at the expense of fruit development. The optimal time for nitrogen application is when vines demonstrate the strongest demand — early in the season or when the first 5-7 leaves have unfolded and leading into bloom. However, for vines exhibiting borderline nitrogen deficiency, foliar nitrogen can help with some symptoms and improve yeast assimilable nitrogen in your fruit if needed.
- Incorrectly Removing Nutrient-Deficient Leaves
Identifying and correctly diagnosing nutrient deficiencies requires a nuanced approach. Removing leaves that show signs of deficiency (e.g., chlorosis) without understanding the underlying issue does not solve the nutritional issue at hand. You don’t want to take off symptomatic leaves because the plant is trying to export its mobile nutrients before the leaf falls off. Send your plant tissue samples to a lab for a progress report on your nutrition status for the year.
- Letting Late Season Weeds Get Out of Control
Weeds vying for water and nutrients can substantially impact vine health and fruit ripening, particularly in the competition with younger vines. Your goal for summer weed management should be to have it under control as you’re approaching veraison, so once you get into veraison to harvest, you can focus on monitoring the fruit, monitoring diseases in your grapes, and getting ready for harvest. Always check the pre-harvest interval (PHI) of any herbicides you are using close to harvest time.
If you want to learn more about midsummer mismanagement in the vineyard, check out https://www.vineyardundergroundpodcast.com/vu049.
