2003 Results

Overall, more striped and spotted beetles visited fields with 'Turk's Turban' than fields with just melons (p<0.05).  This means that our trap crop makes a melon field a regional attractant to beetles.  However, having more beetles in a trap cropped field is only a problem if they move from the trap crop plants to melon plants.  We found that there were more striped beetles in trap crop rows than in melon rows throughout the season, but there were the same number of beetles on melon rows in the trap crop and control fields.  Furthermore, melon rows more distant from the trap crop rows had no fewer beetles in them than rows right next to trap crop rows.  The trap crop attracts more beetles to the field, but doesn't thoroughly distract them from the melon plants.  Consequently, there was the same average number of wilted plants in melon rows from fields with and without the trap crop. 

We hoped to slow the dispersal of beetles from trap crop plants to melon plants by making weekly sprays of insecticide in the trap crop in one field.  These sprays did not reduce average number of beetles or wilted plants in melon rows when compared to unsprayed rows.  From average beetle counts and wilt ratings, that a 'Turk's Turban' trap crop, sprayed or unsprayed, does not decrease the incidence of bacterial wilt in muskmelon.

Yield data from these three fields, however, show that the field without a trap crop and the insecticide-treated trap crop field produced a greater number and total weight of melons than did the unsprayed trap crop field.  Our average beetle counts and wilt data do not reflect this trend, so we tracked beetle populations and bacterial wilt development over time for each field. For the first two rating dates with wilt signs (fourth and fifth), the unsprayed trap crop field had significantly more bacterial wilt incidence than the control or sprayed trap crop plots.  Perhaps this early infection had a great impact on yield.

Oddly, there was no correlation between bacterial wilt development and beetle population dynamics this season (P<0.05).  This may have occurred because beetle populations were very low, a phenomenon which may also have masked the impact of our treatments.  We did note that the population of striped beetles on melon plants in the trap crop fields appeared to increase sharply when most of the trap crop wilted.  This shows that to effectively use this trap crop, we will need to keep it alive for the entire season.