Avocado growers are being urged to prepare their orchards now to protect them from spring and summer rains and prevent crop losses.
Avocados Australia chief executive John Tyas said the fruit trees were highly susceptible to drowning in wet conditions, which could lead to reduced availability of fruit. "The real problem with rain at this time of year, you've got trees that are flowering and setting fruit, so they're very susceptible to disease," he said. "Avocado trees are very susceptible to just drowning, they can't have waterlogged conditions for more than a couple of days otherwise they'll keel over. At a recent field day in Bundaberg, Queensland Department of Agriculture extension horticulturist Simon Newett outlined the risks of over-watering and high rainfall. "While [avocado] has a big need for water, it also is very sensitive to over-irrigation, not only from encouraging phytophthora root rot, but also from basically asphyxiating the roots," he said. "Avocado roots have a very high oxygen requirement. "It's a fine line, it has to be managed very well and very balanced." He said growers that had not prepared for wet conditions could be vulnerable to phytophthora, a soil fungus that causes root rot and could kill out entire orchards in a single season of heavy rain. "Avocado evolved in Central America, and the phytophthora organism, pathogen, they think evolved in the New Guinea area," he said. "We do have some root stocks that are more tolerant than others, but it's extremely susceptible to phytophthora." He said the impact could be devastating. "I think we've seen in the Bundaberg area when we had the really wet weather probably four years ago, that has impacted on yields for three years and they're only just coming out of them," he said. Over the next three months most growing regions are likely to see average rainfall, but the weather bureau is on La Nina watch. Avocados Australia chief executive John Tyas said growers should take steps now to ensure any rain they do receive in coming months works for them and not against them, especially if they are new to the industry. "There's a whole lot of things growers can do from selecting the right site, avocados are really dependent on really deep well-drained soils and a good supply of good quality water," he said. "Then there's a whole range of management practices, making sure that growers mound their orchards, make sure that they put good drainage systems in. "If all those things are done then it's quite manageable."
