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Now is the Time to Plant Annual Habitat | 19
BASIC growers are being encouraged to plant annual habitat hedgerows along their field margins and the time to plant is now. Last season, 23 out of the 30 enrolled fields had at least one field margin planted in annual habitat. Those remaining fields used strip cutting of alfalfa to increase and maintain the diversity of natural enemies in their cotton.

The planting of annual habitat can create a local ecosystem which more closely emulates natural ecosystems, and promotes the in-field production of millions (per acre) of voracious pest-eating beneficials at no additional cost to cotton growers. This free source of indigenous natural enemies, which would be prohibitively expensive to purchase, helps control the pest numbers in cotton.

Plant Variety
Cotton interplanted with or growing adjacent to unsprayed alfalfa hay, corn, cowpeas, sunflower borders, sorghum and mustard attracts a wide variety of natural enemies. These can include lady beetles, green lacewings, Tachinid flies, big-eyed bugs, spiders, pirate bugs, predacious beetles and many other predators that can effectively control sweet potato whitefly, bollworm, cotton aphids and other potential pests.

Risk?
It may seem risky or unnecessary to plant other crop species along field margins, but research continues to support the idea that increasing species diversity attracts and supports naturally occurring beneficials who work in your fields for free. Rachel Long, UCCE Farm Advisor notes in a publication about the use of hedgerows that “California farmers are interested in planting insectary hedgerows to attract beneficial insects for better biocontrol of pests in adjacent crops.” She does acknowledge that some growers are concerned about attracting more pests to their farms with hedgerow plantings. Her work found that while some pests are found in the hedgerows, data show that insectary plants are not contributing to a build-up of pests on farms. Most pests were found mid-to-late in the season, and few were found to reproduce on the plants, especially early in the season. Instead, the insectary hedgerows in our study favored beneficial insects over pests, by a ratio of three to one. Her work was done with perennial plants, but the principles of additional habitat remain the same.

Integrated Methods
Rincon-Vitova producers of beneficial insects advises cotton growers to work closely with PCAs skilled in IPM methods such as beneficial insect releases, mating disruption, selective pesticides easy on beneficials, and spot spraying. If it is necessary to knock runaway pest populations down to levels that small populations of newly-introduced beneficials can easily mop up, use least-toxic, low-residual spray materials. The goal of spraying (selective use of pesticides least toxic to beneficials) is lowering pest populations to tolerable levels, not pest eradication. Low pest populations and innocuous alternate prey are necessary to feed biological control organisms.

For those using alfalfa as a border, strip cutting fields adjacent to cotton is a must. Strip cutting (harvesting alternate strips or fields) stabilizes the alfalfa agro-ecosystem, with different-aged hay growths occurring simultaneously in the same or nearby fields. When one strip is cut, alternate strips or fields are half grown, and fields and farms are never completely bare or without an alfalfa breeding refuge for beneficials.

Harvesting alternate strips keeps plants producing predators and parasites throughout the season, sending a steady migration of beneficials into nearby cotton. This "battle of the bugs" takes place without damage to cotton. Alfalfa is also an excellent Lygus trap crop. Cutting an entire alfalfa field at one time forces Lygus bugs to fly into neighboring crops. Nearby uncut alfalfa as a trap crop eliminates the need to spray cotton for Lygus.

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