EVALUATION OF SEVERAL PEAR PSYLLA CONTROL 

 PROGRAMS IN CONNECTICUT 



Roger G. Adams and David A. Kollas 

 Plant Science Department 

 University of Connecticut 

 Storrs 



The adult pear psylla is dark reddish-brown, about 1/10 inch 

 long, and looks like a miniature cicada. They overwinter under 

 the bark of pear trees and in other sheltered areas. Yellow, 

 rice- grain shaped eggs are first deposited on fruit spurs, but as 

 the buds open eggs are laid on exposed leaf tissue. There are 

 five instars or nymphal stages. The first four instars feed on 

 plant sap and excrete a drop of clear colored, sticky honeydew 

 liquid around their bodies. The fifth instar is not surrounded with 

 honeydew and is called the "hardshell" stage. It is dark brown 

 with prominent wing pads. The earlier instars range in color 

 from yellow to greenish-brown. About one month is required to 

 complete the life cycle. There are several generations each year. 



The pear psylla was first reported in the United States from 

 Connecticut in 1S32. Since that time it has become the most im- 

 portant insect pest of pears in North America. 



The pear psylla has become resistant to many form.erly effective 

 insecticides, thus making control increasingly difficult. 



Five treatment programs and a check were evaluated in 1979 for 

 the control of the pear psylla on 18- year- old Bartlett pears at the 

 University of Connecticut Spring Hill Orchard in Storrs. The treat- 

 ment programs, dosage rates, and dates of application are presented 

 in Table 1 on the following page. All insecticide treatments were 

 applied as dilute sprays by handgun. Five, single-tree replicates 

 were used per treatment. 



To sample for eggs and nymphs, 4 spurs per tree (one from each 

 quadrant) were collected and brought back to the lab where pear 

 psyllas were counted with the aid of a microscope. Adults were 

 sampled by tapping limbs with a rubber covered piece of wood and 

 recording the number of adults falling onto an 18 by 18 inch cloth- 

 covered frame. One tap per limb was used from four locations per 

 tree. On July 27, 1979 tree limbs and leaves were visually examined 

 and rated for the presence of honeydew and sooty mold. The following 

 damage index scale was used: = clean; 1 to 2 = light; 3 to 4 = mod- 

 erate; 5 to 6 = heavy. Percent clean fruit was determined by examin- 

 ing 20 fruits per tree. 



