Effect of host plant makeup through nitrogen fertilization and growth regulators on the pear psylla population

Abstract

The pear psylla, Cacopsylla bidens (Sulc), is one of the most damaging pests of commercial pear orchards in Israel. However, growers today have only two pesticides left to control the pear psylla, therefore alternative control methods are needed. Our goal was to find ways to control the psylla population through rational use of cultural control methods: manipulating the levels of nitrogen fertilization, and using growth regulators. Our objectives were to determine the impact of nitrogen fertilization level on pear psylla populations, the impact of application of plant growth regulators (clormequat chloride and prohexadion-calcium) on psylla populations, and whether there is an interaction between the two factors in a semi-field-scale and in field-scale experiments. Higher oviposition and nymph development rates were found in trees that had higher leaf-nitrogen contents. Lower oviposition, nymph survival, and nymph development rates were found in trees that were treated with growth regulators. The suppress...