Survey of insect pests on crops

Survey of insect pests on crops in organic plot at WWAREC, summer 2006

Tomato: Twenty plants from the plot were randomly selected and one compound leaf and fruit per plant was selected for examination by counting down three leaves from the terminal leaf and selecting a mature, whole leaf and counting all insects and/or mites present. Plants were monitored at approximately seven day intervals during the morning on each survey date, 8:00 to 11:00 am. Average number of each pest species present was calculated for each survey date and results are reported in the following table.

As indicated in the table, very few insect or mite pests were noted during surveys on any date. However the increasing number of aphids on plants from 1 to 8 June were of concern and applications of a Neem based insecticide were made to plants in the plot to manage and reduce numbers of aphids. Numbers declined on 26 June, probably in response to the Neem insecticide applications. During June workers in the tomato field noted a large number of blister beetles feeding on plants in one small location and this population was sprayed with a mixture of a pyrethrum and Spinosad based insecticide on two dates at a two day interval. Numerous dead adult beetles were found on the ground following the application and no live beetles were found feeding on plants indicating that the insecticides killed the majority of the beetles. Results of surveys of fruit indicated very low incidence of insect damaged fruit.

Insect Pest	26 May	1 June	8 June	16 June	26 June	30 June	7 July	14 July	21 July
Aphids	0	0.2 / 0.4	0.35 / 0.59	0.45 / 0.76	0	0.1 / 0.3	0.15 / 0.49	0.1 / 0.3	0.1 / 0.3
Caterpillars	0	0	0	0	0	0	0	0	0
Thrips	0.05 / 0.22	0	0.05 / 0.22	0	0	0	0.1 / 0.3	0	0
Beetles	0.05 / 0.22	0	0	0	0	0	0	0	0

Watermelon: Twenty plants from the plot were randomly selected and one leaf per plant was selected for examination by counting down three leaves from the terminal leaf and selecting a mature, whole leaf and counting all insects and/or mites present. Plants were monitored at approximately seven day intervals during the morning on each survey date, 8:00 to 11:00 am. Average number of each pest species present was calculated for each survey date and results are reported in the following table.

Plants were monitored from 30 June to 21 July. An adult squash bug was noted on plants on three dates, a cucumber beetle was noted on two dates and few to no aphids or mites were found on plants. No insect or mite control treatments were initiated.

Southern peas: Twenty mature plants from the plot were randomly selected and one leaf and pod per plant was selected for examination by counting down three leaves from the terminal leaf and selecting a mature, whole leaf and counting all insects and/or mites present. Mature plants were examined on 14 and 21 July during the morning on each survey date, 8:00 to 11:00 am. Average number of each pest species present was calculated for each survey date and results are reported in the following table.

Few to no insect or mite pests were found on plant foliage or pods. No control measures for insect or mite pests were initiated.

Sweet corn: Twenty plants from each of two planting date plots within the field were randomly selected and examined for all insects and/or mites present. Plants were monitored at approximately seven day intervals during the morning on each survey date, 8:00 to 11:00 am. Average number of each pest species present was calculated for each survey date and results are reported in the following table. Mature corn ears from each of 50 randomly selected plants were removed and husks removed to examine ears for insects and damage. Number of corn earworm larvae per ear and percent of each ear with damage to kernels was recorded. Average number of earworm larvae per ear and average percent damage to each ear was calculated and reported in the following table.

No significantly large numbers of insect pests were noted on plant foliage during surveys from 1 June through 28 June. Entrust insecticide was applied to plants at 2-3 day intervals from the time that tassels were apparent on the majority of plants in each of the two planting date plots until the silk on ears was brown and dry. Results of examinations of ears for earworm larvae and damage indicated that there were 0.4 (+0.67) larvae per ear resulting in 11% (+7.1) kernel damage to the tip of the ear in the earliest planting. In the second planting there were 1.7 (+1.2) larvae per ear resulting in 7.3% (+3.5) kernel damage to the tip of the ear.