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The pest and disease cycle


Graphic - The pest and disease cycle

There is much research that has helped us understand the role that human activity plays in the spread of pests and disease.

Phytophthora infections in European nurseries

A sample of 732 nurseries in 18 European countries showed that nearly all (91.5%) had at least one species of phytophthora. Appropriate planning and careful sourcing can minimise the amount of infected stock and ensure that only healthy trees are planted.

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The impact of dirty tools

Disease can be spread on our tools. In a Brazilian study, plots of unharvested eucalyptus had only a 2.7% occurrence of Ceratocystis wilt, but harvested plots had 39.7%. This suggests the disease had been spread on infected harvesting tools. In a USA study, Ceratocystis platani infected 40% of wounds made by saws which had been previously used on diseased trees. Rates increased to 50% for climbing ropes.

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Clean start, every day

In a study of seven sites, the rate of tree infection by Phytophthora lateralis reduced over 12 years from 29% to 0% where vehicles and boots were washed. Sites where no washing was done saw only limited reductions.

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Time to act

In 2014-15 at least 300ha of woodland in England were felled to stop the spread of a pest or disease. A dramatic increase in the number and presence of non-native pests and diseases over recent years demonstrates that our nation’s woodlands and forests need greater protection.

Clean boots, clean forests

A study in a phytophthora control zone found that 30% of boots sampled contained infected organic material. Phytophthora can survive for more than a year in organic material, increasing the chances of its becoming established elsewhere if the material is moved. Cleaning boots, tools and vehicles bas been shown to successfully reduce the number of phytophthora sites, and is therefore recommended.

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Last updated: 19th September 2017