Broccoli- Flea Beetle Exclusion

flea beetle damage to broccoli seedling

 

Introduction:

Western flea beetle is a significant pest on broccoli and other brassicas in Colorado and precludes direct seeding of these crops, especially under organic production systems. Alternatively transplanted crops allow the plant to survive early flea beetle infestation. In this experiment, direct seeding with floating row cover intended to exclude early infestation by flea beetle on the broccoli plants was compared with the common practice of using transplants.

Methods:

On May 25, 2005, Packman and Premium Crop broccoli seeds were planted in the greenhouse and in the field. The direct seeded crop was immediately covered with floating row cover (1/2 oz./yard weight). At three-leaf stage the greenhouse grown transplants were transplanted to the field on June 22, 2005. The direct seeded plants emerged and grew at the same rate as the transplants. Flea beetles were effectively excluded from the field planted broccoli. Both treatments were planted double rows per bed with a single drip line used for irrigation. The transplanted treatment was blind cultivated before transplanting. Approximately 6 weeks after direct seeding, the floating row cover was removed.

As seen in the photo, weed emergence and growth coincided with the direct seeded broccoli emergence, resulting in significant weed pressure. Weeds were hand removed and the broccoli thinned to 10″ spacing. At this point the development of the broccoli in both treatments was similar. Time to development and yield under both treatments were similar. weedy direct seeded broccoli under fleece

Costs:

Put in costs here

Cost comparisons; transplant cost; transplanting cost

direct seeding cost; floating row cover cost, weeding and thinning cost

Discussion:

Cost of producing transplants and transplanting was lower than the combined cost of floating row cover, weeding, and thinning under organic practices. Certainly, pre-emergent herbicides in a conventional system would result in reduced weeding labor costs.

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