Voltage Gradients in Trees as an Indicator of Susceptibility to Insect Attack
Voltage gradients in trees may be used to determine their physiological condition and hence their susceptibility to insect attack. Field measurements with a portable vacuum-tube millivoltmeter have shown that in normal trees the voltage gradient is positive in the spring but becomes negative later in the summer. In trees which are subnormal, but with no external evidence of lowered vitality, the cycle is at least partially reversed. The importance of these findings in insect control is obvious.
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Document Type: Journal Article
Affiliations: Assistant Entomologist, Division of Forest Insect Investigations, Bureau of Entomology and Plant Quarantine, New Haven, Conn.
Publication date: 01 June 1943