Insect Thresholds of Sugarbeets

Pest

Threshold

Reference

armyworms

     mid-May through June

     July through August

     September

1-3 caterpillars per plant

3-5 caterpillars per plant

more than 5 per plant

Proceedings UI Winter Commodity Schools (1986)

black bean aphid

Depends on contract price, cost of insecticide, and months until harvest -

Extrapolated from Proceedings of UI Winter Commodity Schools (1984)

     1 month before harvest

25% plants with aphids on at least 4 new leaves

     2-3 months before harvest

8-12% plants with aphids on at least 4 new leaves

     4 months before harvest

5% plants with aphids on at least 4 new leaves,

University of California IPM Pest Management Database (1998)University of California IPM Pest Management Database (1998)

     plants 2-3 months old  

treat if leaf margins are curled, aphids are present on most leaves, and infestations cover 20-40% of leaf surface

     plants 3-4 months old

treat if leaves are severely curled, aphids are present on all leaves and infestations cover 40-60% of leaf surface

     older plants

as above, but infestations cover 60-80% of leaf surface

sugarbeet crown borer

10 or more months per day per pheromone trap for 7 consecutive days before 8 May

Proceedings UI Winter Commodity Schools (1993)

sugarbeet root maggot

40-45 flies per sticky stake trap from beginning of season until peak capture (threshold depends on beet contract price and cost of insecticide)

UI CIS 999 (1993)

sugarbeet webworm

1-2 caterpillars per leaf on at least half of plants

Unknown (unreferenced data from files of E.J. Bechinski)