Monday, June 3, 2013 3:08 pm

By BRUCE STEELMAN

Intercropping is a planting technique that farmers and gardeners can use to promote beneficial plant interactions and perhaps reduce the need for pesticides says Dr. Annette Wszelaki, University of Tennessee Extension commercial vegetable specialist and director of UT's organic and sustainable crop production outreach program.

Intercropping is the growing of two or more crops in close proximity to promote beneficial interactions between them, Wszelaki said. "The use of intercropping can provide benefits to a management system, including decreased insect pest pressure, reduced need for external inputs, increases in biodiversity, enhanced production and lower economic risk," she said.

Several spatial arrangements can be used, and plant density, maturity date and plant architecture are considerations:

- Row intercropping refers to two or more crops grown together at the same time with at least one crop planted in rows.

- Strip intercropping refers to growing two or more crops together in strips wide enough to permit separate crop production using machines but close enough for the crops to interact.

- Mixed intercropping has no distinct row or strip arrangements.

- Relay intercropping is used for planting in succession, where a second crop is planted into a standing crop at the reproductive stage before harvesting.

Wszelaki adds that when using intercropping, producers should consider reducing seeding rates to avoid overcrowding. "Rates should also reflect the desired yield for each crop. Staggering planting and/or harvesting dates takes advantage of peak resource demands, reducing competition between crops," she said. This includes plants with a variety of heights and growth patterns and also ensures reduced competition. "For example, a tall corn plant can capture sunlight and create a beneficial understory environment for a low-growing, shade-tolerant species," she said.

The vegetable production expert reminds producers and gardeners to plant species susceptible to certain common pests alongside non-host plants to provide a physical barrier to insect pest movement. "This limits the spread and decreases the likelihood of damage to susceptible varieties. For example, separating plantings of solanaceous crops, such as tomatoes and potatoes, that are susceptible to Colorado potato beetle, with a non-host crop such as corn, can reduce the movement of Colorado potato beetles from one solanaceous crop to another."

Wszelaki adds that planting multiple species enhances biodiversity and encourages beneficial insect populations that can offer natural biocontrol. "Beneficial interactions between plants can confuse insects, lowering insect pest levels, lessening the extent of damage and reducing the need for external inputs," she said. "Inclusion of multiple crops utilizing different environmental niches increases the productivity per unit of land, allowing for financial diversification, as well as a reduced financial risk in the event of crop failure."

More information about intercropping is available from Cannon County UT Extension Office or online in in a fact sheet co-authored by Wszelaki, Trap Crops, Intercropping and Companion Planting, UT Extension publication W235-F, available online at

https://utextension.tennessee.edu/publications/Documents/W235-F.pdf

Bruce Steelman

614 Lehman Street

Phone: 615-563-2554

E:mail- tsteelm2@utk.edu