Time of Tuber Infestation and Relationships Between Pheromone Catches of Adult Moths, Foliar Larval Populations, and Tuber Damage by the Potato Tuberworm1

Time of tuber infestation by Phthorimaea operculella (Zeller) was markedly affected by the type of irrigation system employed. Tuber infestation under furrow irrigation was above 25% for 4 wk prior to vine senescence while sprinkler irrigated potatoes sustained less than 5% damage during this period. After irrigation was terminated, infestation increased rapidly in sprinkler irrigated plots. Tuber infestation continued to increase in all irrigation blocks late in the season, but rows which were hilled and rolled sustained less damage than ones which were only rolled. Larval populations in the foliage and moth counts in pheromone traps increased during the season and were significantly correlated. Under furrow irrigation, pheromone trap catches and larval counts in the foliage were significantly correlated with tuber damage.