CULTURAL TIP: BRACING GROVES FOR THE COLD
With the recent onslaught of cold and wet weather - and likely more to come - following are several cultural‐management tips for the winter season:
- Freeze - Be very aware of temperatures falling below 30‐degrees Fahrenheit, regardless of weather forecasts. Rather than rely on forecasts, it is advised to establish a frost‐management plan, and follow it. The Fact Sheet on Freeze Protection for Avocados contains useful information, and, if you don't already own one, please download such from the website: http://www.californiaavocadogrowers.com/assets/Uploads/Growers‐Site/Fact‐Sheets/Fact‐Sheet‐Freeze.pdf. Key points to consider, when preparing for a freeze, are: 1) prevent trees from experiencing water stress 2) keep soils surrounding trees clear 3) and healthy, well‐nourished trees recover faster. It is worthwhile to control freeze effects, as the damage a freeze inflicts is insidious and can reduce flowering in spring.
- Wet Soils - Increased rain is often beneficial in recharging dry soils and reducing salinity. However, heavy rainfall also can be detrimental, as slow‐drying soils can result in stressed trees; raising the chance for root rot. Be on the lookout for premature leaf drop, trees bearing small and pale green leaves and shoot die back, without a freeze. Overall, impaired trees will take on an "unhealthy" look (as pictured to the right), and these trees should be treated for root rot at the beginning of spring. If not properly treated, these trees will flower excessively in spring; but fail to flush.
- Cold, Sunny Days - When grove temperatures are cold (generally below 60‐degrees Fahrenheit) and the day very sunny, avocado leaves can stress and bleach or yellow. This is due to excessive light, versus the temperature, wherein the leaves cannot metabolize all light being received. The leaves, in turn, produce hydrogen peroxide, which damages the leaves. Therefore, it is important to maintain good, healthy, green and productive leaves, as these leaves can help trees accumulate starch; which then assists trees with flowering and fruit set in spring. If the leaves yellow during winter, it is advised to consider reviewing your nutrient program.
