populations are primarily composed of mature 

 flies. To clarify conclusions on trap type 

 effectiveness for AMF, we conducted the 

 following experiment during the summer of 

 1997. 



Materials & Methods 



In nine rows of apple trees in a commercial 

 orchard in Massachusetts, the first six trees in 

 each row (i.e. trees nearest adjacent woods) 

 were selected for use. In the first row, the first 

 tree contained a red sphere (8 cm in diameter) 

 placed in optimal position (surrounded by as 

 much foliage and fruit as possible at a distance 

 of 3-6 inches), in the mid-portion of the tree 

 canopy. The second tree contained a red sphere 

 in poor position (few leaves and no fruit 

 nearby). The third and fourth trees contained a 

 Ladd trap (9 cm diameter red sphere centered 

 on a 9x1 1-inch yellow panel) in optimal and 

 poor position, respectively. The fifth and sixth 

 trees contained a yellow panel (9x1 1-inch 

 rectangle) in optimal and poor position, 

 respectively. For every succeeding row, trap 

 positions were rotated so that each trap type 

 appeared in each within-row tree position three 

 times. 



In every row, poor position was 



standardized for all traps, either low and out; 

 high and out; or close to the trunk, high or low. 

 A vial containing butyl hexanoate was placed 4 

 to 6 inches away from every trap. Traps were 

 serviced every week for six weeks, during 

 which flies were removed and counted and 

 sticky was replenished if needed. The 

 experiment was conducted from late July to 

 early September. 



Results 



Overall, red spheres in both optimal and 

 poor positions and Ladd traps in optimal 

 position caught similar numbers of flies and 

 three times more flies than Ladd traps in poor 

 position or yellow panels in either positions 

 (Table 1). During the first three weeks, red 

 spheres in optimal position caught numerically 

 more flies than red spheres in poor position and 



Ladd traps in optimal position; the difference, 

 however, was not significant. During the last 

 three weeks, as fruit reached maturity, red 

 spheres in optimal position caught numerically 

 fewer flies than red spheres in poor position 

 and Ladd traps in optimal position; again 

 however, the difference was not significant. 

 Across all six weeks Ladd traps in poor position 

 and yellow panels in either position caught 

 significantly fewer flies than red spheres in 

 either position and Ladd traps in optimal 

 position. 



Conclusions 



From late July to mid-August, red spheres 

 in optimal position caught 35-40% more AMF 

 than red spheres in poor position or Ladd traps 

 in optimal position. The proximity of foliage 

 and fruit to red spheres in optimal position 

 probably facilitated more frequent opportunity 

 for AMF to encounter such spheres. This could 

 explain the numerical difference in capture 

 between red spheres in optimal position versus 

 red spheres in poor position. Yellow panels 

 were comparatively unattractive irrespective 

 of panel position. Ladd traps in poor position 

 caught numbers of AMF similar to those on 

 yellow panels. Apparently, in poor position, the 

 red sphere component of a Ladd trap is not 

 perceived as fruit by foraging AMF. 



By mid-August, the Paulared apples on the 

 trapped trees had turned red and visually 

 competed with red spheres in optimal position. 

 At times, red sphere traps in optimal position 

 were difficult for us to find in the trees. At that 

 point, red spheres in poor position (placed 

 farther away from competing fruit) and Ladd 

 traps in optimal position began to capture more 

 AMF than red spheres in optimal position. 

 Ladd traps in optimal position might have 

 enhanced the contrast of a red sphere against 

 background by furnishing a yellow panel or 

 background rather than red fruit. The effect 

 could not be reproduced by Ladd traps in poor 

 position. 



Efficiency of red spheres for trapping AMF 

 seems to decrease when fruit reaches a size and 

 color similar to the spheres. This factor 



Fruit Notes, Volume 62 (Number 4), Fall, 1997 



19 



