Water is still lying around in orchards, after the recent heavy rains and flooding in Victoria. This unseasonal event has delayed the work being done by NetPro in Adelaide Hills and Shepparton.
Not only is this unseasonal wet spell affecting construction of protective structures, it is of major concern, because of the effects on the crops that have become swamped with water.
Research in flooded soils has shown that the oxygen concentration approaches zero after 24 hours (however, moderate water movement allows some oxygen to get to the plants, and damage is not as severe.) Without oxygen, the plant cannot perform critical life-sustaining functions such as respiration, water uptake, root growth, etc. Water-logging also leads to accumulations of compounds like CO2, which are toxic to plants in high concentrations.
Growth is a critical factor in survivability due to flooding. Technically, the larger a plant, the more oxygen it requires to stay alive.
Lately Victoria has had drier weather, but not warm weather. As the orchards are now producing flowers, the trees are suffering with cooler than usual temperatures. The overcast and cooler conditions are also hindering Bee Activity critical for pollination.
Cloudy conditions decrease solar radiation and keep soils and floodwaters cooler.
As the temperatures increase this favours disease development. Apart from root rot issues, many fruit and leaf diseases are more active in wet, humid conditions. Where water is laying or soils are waterlogged, humidity will be higher adding to disease pressure and this humidity will bring the next wave of issues for Victorian orchardists as the season lengthens.