Tissue testing

In addition to the customary testing of leaves at bloom to check the vine’s nutrient status, he suggest doing it again during veraison. This takes advantage of research data and improved technology that now allow for more precise applications of water and nutrients than can be done based only on an early-season sample. A veraison leaf test offers a way to double-check the vine’s nutrient status and correct it, as needed, going into harvest.

Weed Control

Unlike flood irrigation, in which the berms remain dry and the lack of moisture helps limit weed growth, drip irrigation can contribute to weed problems by keeping the soils moist. This extra water not only encourages “escapes” to germinate and grow but it also accelerates breakdown of residual herbicides applied early in the season, reducing the length of their effectiveness. Keeping an eye on the berms and spot spraying as needed can help prevent perennial or noxious weeds from going to seed later in the summer. Plus, it helps minimize development of weed resistance to the herbicides, Verdegaal says.

Insect Control

In many cases, good soil moisture levels earlier in the season contributed to vigorous vine growth that may have helped keep mites from attacking the vines. However, with summer’s dry conditions and heat spells, their numbers can build quickly. That’s why it’s important to continue monitoring vineyards and be ready to respond promptly to prevent any flare-ups, Verdegaal notes.

As for pressure from various leafhopper species, by the time veraison has begun growers may have already helped reduce that threat when they treated their vineyards earlier in the season to control the vine mealybug. “Many growers who treat for the vine mealybug seem to get pretty good incidental control of leafhoppers,” he says.

Communication

Verdegaal offers one more tip to keep in mind before grape picking begins: “Remember,” he says, “stay in contact with your grape buyer or winery reps to avoid misunderstandings and major problems during the “controlled” confusion of harvest.”