Exclusion fences reduce colonization of carrots by the carrot rust fly, Psila rosae (Diptera: Psilidae)

The effectiveness of exclusion fences in preventing the colonization of carrot plantings by the carrot rust fly, Psila rosae (F.), was tested in small field plots. Fenced enclosures were surrounded by panels of mesh nylon window screen l20cm high. Control enclosures were left unfenced. Although the number of first generation P. rosae adults captured on yellow sticky traps was not significantly different between control and fenced enclosures, the number of second generation adults emerging within enclosures was significantly higher in control enclosures than in fenced enclosures. The percentage of unmarketable carrots, % damaged carrots, % urunarketable yield, % damaged yield, and number of lesions per carrot werc all significantly higher In control enclosures than in fenced enclosures. We conclude that exclusion fences impede the colonization of carrot plantings by P. rosae and reduce damage to carrots. The results are discussed as they relate to pest management methods for thc carrot rust fly