Alternatives to Insecticides for Control of Garden Pests

Alternatives to Insecticides for Control of Garden Pests

Principal Investigators:
Richard C. Funt, Professor, Horticulture & Crop Science
Mike McCullough, Graduate Student, Horticulture & Crop Science
Celeste Welty, Assistant Professor, Entomology
Mark Bennett, Associate Professor, Horticulture & Crop Science
Abstract:
The traditional recommendation for controlling pests that injure plants in home gardens is to protect plants by treating with insecticide. Gardeners and extension agents are often frustrated by the lack of research-based information about efficacy of non-chemical alternatives for garden pest management. The objective of this project was to evaluate non-chemical strategies of interest to gardeners, specifically the effect of repellents and row covers on pests that attack snap beans. In this first year of the two-year project, evaluations were done in plots on campus at the Lane Avenue Horticulture Farm; the plan to conduct experiments in private gardens was postponed until the second year.

This project focused on evaluating efficacy of garlic and hot pepper repellents on pod and leaf feeding by the bean leaf beetle, Mexican bean beetle, and potato leafhopper on snap beans. Treatments included low, moderate, and high rates of garlic and hot pepper, each applied on a high intensity schedule (sprayed five times) and a low intensity schedule (sprayed weekly). These repellents were compared with conventional insecticide, with lightweight row covers that excluded pests, and with untreated controls. There were four replicates per treatment. Beans were planted on 8 June and harvested on 3 August. Plots were scouted weekly for pests. At harvest, six plants per plot were evaluated for quality and yield. Harvest results are summarized in Table 1. Analysis of harvest and scouting data will be completed by January 1995.

Extension Program Implementation:

Results of the 1994 trial will be shared with extension agents and Master Gardeners via the Ohio Master Gardener Newsletter. After the second season in 1995, conclusions will be incorporated into a new Extension FactSheet on management of snap bean pests.

Harvest Results -- Mean of Four REPS
	Number of beans per plant		Bean Yield (grams)		Plant Dry Weight
Treatment	Marketable	Unmarketable	Marketable	Unmarketable	(Grams)
Plain Water	7	3	33	13	152
Insecticidal Dust	19	3	98	13	158
Rowcover	6	1	33	3	63
Control	11	7	57	30	145
Garlic 1/3x	9	5	41	26	135
Garlic x weekly	12	5	59	22	140
Garlic 3x weekly	12	6	58	32	148
Garlic 1/3x twice	11	6	58	28	146
Garlic x twice	11	4	57	19	138
Garlic 3x twice	10	5	52	25	131
Pepper 1/3x	9	5	44	24	127
Pepper x weekly	10	5	49	22	118
Pepper 3x	10	4	53	18	134
Pepper 1/3x	11	5	56	22	129
Pepper x twice	11	5	56	22	139
Pepper 3x twice	9	5	44	25	132


	% of Foliage	% of foliage with beetle feeding
	with Leafhopper
Treatment	damage	0%	1-10%	10-50%	>50%
Plain Water	23	13	43	30	14
Insecticidal Dust	23	30	64	5	1
Rowcover	1	52	42	5	1
Control	30	13	51	31	5
Garlic 1/3x	34	13	49	28	10
Garlic x weekly	29	19	49	22	11
Garlic 3x weekly	24	14	51	25	11
Garlic 1/3x twice	31	11	62	22	5
Garlic x twice	29	13	60	22	5
Garlic 3 twice	31	12	53	27	8
Pepper 1/3x	32	11	57	26	6
Pepper x weekly	28	12	57	25	6
Pepper 3x	27	15	60	20	6
Pepper 1/3x	31	12	58	24	7
Pepper x twice	23	15	60	19	7
Pepper 3x twice	28	13	54	24	10

For further information contact Richard C. Funt , Professor, Dept. of Horticulture & Crop Science, The Ohio State University or the Ohio IPM Office.

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