• With a relatively warm autumn, greenhouse thrips have been persistent this season, and may still be residing in some blocks. Likewise, six-spotted mite (SSM) will over-winter in most orchards, particularly in warmer areas, so reducing populations before spring arrives is a good idea.
• Maintain a copper fungicide cover with products such as Kocide® Opti or Tri-Base Blue® through winter to protect against anthracnose infection as some species continue to infect even at low temperatures. »»Next season’s fertiliser applications start soon, with base applications generally beginning in winter. To design a programme that corrects existing imbalances and feeds next season’s crop, soil tests should be completed as soon as possible.
• Tree stress, low nutrition, Phytophthora infection, heavy crop load and SSM infestation Avocados can increase a tree’s susceptibility to frost damage during winter months. If your property is at risk,  ensure adequate frostfighting measures are in place. Options include overhead watering, wind machines, frost covers on young trees or application of low-biuret urea. 

Leaf yellowing may occur during winter months and can be a sign of low nitrogen availability. Cool soil conditions limit root uptake of nitrogen, and heavy rain causes  losses of available nitrate through leaching. Rectifying the nitrogen status of trees with foliar nitrogen may help alleviate biennial bearing tendencies.

International research shows that foliar applications of urea may also increase an avocado tree’s resistance to frost damage  (see photo) in light frosts. Urea is the  most efficient form of nitrogen for leaf  absorption, but low-biuret products (i.e. technical grade) must be used, as biuret (a nitrogenous bi-product) is phytotoxic to plants. Yara Safe-N is also a good option, as part of the nitrogen content is slow-release. Magnesium sulphate (Epsom salts) may also be added to improve leaf greening as required.