What is in this article?:
- Managing grapevine frost risks by the numbers
- Irrigation during frost
- Here's a bit of help in planning grapevine frost protection this spring, thanks to research by Matthew Fidelibus, UCCE specialist, Kearney Agricultural Research & Extension Center; and Stephen Vasquez, formerly Fresno County UCCE farm advisor for viticulture.
Irrigation during frost
Native vegetation or cover crops that insulate soils from absorbing heat should be mowed, disked, and irrigated, unless significant precipitation makes irrigation unnecessary.
Irrigation during a frost event can be beneficial. On nights when low temperatures are expected, pumps should be turned on early enough that the entire vineyard is covered with water. In some vineyards, it may not be feasible to saturate the whole vineyard. In such cases, focus efforts on the most susceptible areas, low-lying portions where cold air tends to drain. This improves the chances of protection.
Vineyards that are drip irrigated should not have their row middles cultivated. Drip irrigation should be turned on to wet as much soil as possible. Growers will have to be especially vigilant to the weather forecast in order to start irrigating well in advance of the frost event. Cover crops or native vegetation should be mowed prior to bud break and regularly afterwards until the risk of frost has passed.
Row middles should not be cultivated unless a significant rain event has been predicted. Doing so could result in significant losses if frost should occur. It only takes a single frost event one night at freezing or below to experience a complete loss, Extension farm advisors note.
If a significant frost event occurs and all the green shoots are killed, secondary or tertiary buds will push within one to two weeks. However, secondary and tertiary buds will not be as fruitful as the primary buds and growers can expect substantial losses. Extension recommendations include regular irrigation of vineyards that have experienced significant frost damage to develop a full canopy and prepare them for the following season. Also, also caution Extension farm advisors, vineyards with substantial frost damage should not be neglected.
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