The recent heavy rainfall and flooding events in NSW may cause some immediate damage to trees, but may also have significant long term impacts on citrus orchards, particularly those planted on heavy soils or those with impeded drainage. Previous flooding events in the MIA Previous flooding and high rainfall events occurred in the Murrumbidgee Irrigation Areas (MIA) in the 1930’s and 40’s (during the winter months) and the impacts of those events, combined with a tendency to over-water resulted in considerable decline in tree health and the death of many trees. Survey and research work undertaken by Dr. Lilian Fraser concluded that one of the main causes of tree death and decline was due to infection by the root rot fungus Phytophthora citrophthora.
At that time most citrus trees were grown on rough lemon or sweet orange rootstocks, both of which are highly susceptible to Phytophthora root and collar rots. Tree losses were aggravated by faulty irrigation practices, lack of adequate drainage and uneven soil types (Fraser 1942). Fraser along with horticulturists enton, Bowman and Kebby in the NSW Department of Agriculture soon established that trees on trifoliata rootstock planted in infested soil in the MIA made very good growth.
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Source:
Sandra Hardy, Pat Barkley, Andrew Creek, Nerida Donovan
Published by the Department of Primary Industries
