An experiment was done to investigate conditions under which maleic hydrazide fails to give adequate control of runners in strawberry plantations. In a second experiment the effect of applications of maleic hydrazide on flower initiation in the strawberry was studied.
One of the causes of reduced runner inhibition was thought to be the presence of runners already rooted at the start of treatment. To test this possibility, large plants of the variety Talisman were allowed to develop runner chains and were then treated with maleic hydrazide at 2, 4, 6 or 8 mg. per plant. Runners rooted when the experiment began were very resistant to inhibition and soon recommenced the production of secondary stolons. Stolons which had emerged but not formed roots at the time of treatment, however, were effectively inhibited, as were also those which emerged within two weeks of treatment. It is believed that when runner chains are present maleic hydrazide is translocated rapidly to the tips of the stolons, so that the duration and severity of runner control in other parts of the plant is greatly reduced in comparison to that obtained when the parent plants are free of rooted runners.
In the second experiment, in which the variety used was Auchincruive Climax, the formation of flower initials was inhibited by maleic hydrazide at concentrations which did not reduce the rate of leaf initiation. The effect did not persist for more than two plastochrons after treatment, and, provided that care is taken not to spray when flowers are being formed, this capacity for preventing flower truss initiation should not reduce the usefulness of maleic hydrazide for runner control.