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Bring in the Bees: Farmscaping With Pollinator Mixes

By   /  May 2, 2016  /  Comments Off on Bring in the Bees: Farmscaping With Pollinator Mixes

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Dave Wilson, King’s AgriSeeds, co-authored this piece with Genevieve

North Carolina Farm with beefWhy draw more insects to the field? Most row crop fields are acres upon acres of monoculture. If these crops are grown to bloom stage, they will provide food for vitally important pollinators like honeybees for a very short time, and the single plant species creates food for limited insect species. You can use mixes of flowering annuals (like our newly released Summer Solar Mix – a mix of cowpeas, buckwheat, sunflower, and sunn hemp) or perennials (mainly clovers) to create a refuge on the farm to attract diverse species of predatory insects, praying mantises, honey bees, ladybugs, birds, and butterflies. In addition, there are about 4,000 species of wild bees in the US that can be attracted by various blooming species. Both honeybees and wild bees are important agricultural pollinators. Although many farmers want to build organic matter, control erosion, and manage weeds with these flowering cover crops, others will use it primarily for attracting these beneficial species during the summer month. Others may combine this purpose with later use as a forage, preventing nutrient loss, or as a break crop to manage nematodes.

The end goal of farmscaping is pollinator conservation on a field-level scale, which ultimately results in food security and bio-control of harmful crop pests. Most commonly used are blends of flowering commercial cover crops, but permanent native wildflower strips are also used quite effectively.

Active pollinator conservation efforts are excellent defense measures against adverse environmental conditions that include monocultures that limit nectar production and timing over vast acreages, and systemic pesticides that can have sublethal effects like reduced foraging and reproduction.

Implementation

bee - usda_3There is no one right way to start farmscaping, but as a general rule, the larger the area, the better. At least 1-2 acres of farmscaped area per 25 acres of cropland will give you the most benefit. Large, square blocks are the easiest to maintain in terms of edging, weed maintenance, or planting around the edges.

In reality, many configurations will work and what you choose depends on your management, field layout, and topography. Long corridor strips between fields may be the most practical layout.

Most farms have odd-shaped parcels of land that are not easy to bring equipment into for planting and harvest, and these make good areas to dedicate permanently to pollinator crops. These may include small, awkward wedges between a field and a portion of the creek or woods, waterways, hedgerows, diversion strips, farmed terraces, and other fragile areas that are best left alone for the duration of the season and perhaps permanently. Long contour strips could also be taken out of production and planted to a summer annual mix like Summer Solar Mix. They could be more permanent or rotated with other crops. Blooming summer annuals like these will be important for filling in the late summer time of reduced floral resources.

This practice is also well-suited to produce operations, since pollinator plantings can be rotated in alternate succession with the vegetable rows each season. These vegetable systems would also benefit from planting the mix around the perimeter of a greenhouse—both to reduce mowing needs and to draw beneficial insects to the crops planted inside.

In some systems pollinator crops can also be mixed right in, such as overseeding a variety of clovers into thinning pastures. Not only will this boost protein levels of the feed, it will also create staggered bloom times throughout the season.

Using both annual and perennial plantings will fill various bloom windows. Wait until peak bloom or leave strips that will be left to peak bloom. It’s also important to minimize disturbance to long term plantings whenever possible. Make pesticide-free permanent conservation areas a priority. Focus pollinator conservation efforts on areas of the farm that are not often treated with insecticides or vulnerable to spray drift.

Bringing in Bio-Control

In monoculture fields with limited bloom there are few food resources to support natural predatory controls, so pests such as moths and their lepidoptera offspring may begin to dominate the area. Farmscaping draws beneficial predators into adjacent areas so they can begin to move into the field to prey on these pests.

Ground beetles are often generalist predators and prey on slugs, caterpillars, and grasshopper eggs. These beneficial visitors can be encouraged with “beetle banks” – border areas of unmowed grasses and other vegetation.

John Walters of the UK took these photos of a blue beetle eating a slug. The beetle follow a slugs’ slime trail then, when it makes contact, its large pincer jaws grip the unfortunate mollusc. It then injects digestive juices into the slug quickly killing it and turning its insides into ‘slug soup’! The ‘soup’ is then sucked up and within half an hour a slug as large as the beetle can be completely consumed! The larva has rarely been seen but shares the diet of the adult. I once saw one follow and kill a large Ash-black Slug (Limax cineroniger) before devouring it. View video here.

John Walters of the UK took these photos of a blue beetle eating a slug. The beetle follow a slugs’ slime trail then, when it makes contact, its large pincer jaws grip the unfortunate mollusc. It then injects digestive juices into the slug quickly killing it and turning its insides into ‘slug soup’! The ‘soup’ is then sucked up and within half an hour a slug as large as the beetle can be completely consumed! The larva has rarely been seen but shares the diet of the adult. I once saw one follow and kill a large Ash-black Slug (Limax cineroniger) before devouring it. View video here.

In addition to drawing predatory insects, cover crops may also host prey insects that will in turn attract more predatory insects to the field. Many of these predators can have varied diets and will switch prey preference as the rotation moves forward and cash crop pests become available.

However, most crops need enough time to flower to draw effectively large beneficial insect populations. Buckwheat needs to flower for at least 20 days to build up solid populations. This poses a risk of reseeding, since buckwheat starts to set seed 7-10 days after flowering starts. To avoid this problem, you can leave alternating strips growing interspersed with rows where buckwheat is transitioned on time into the next crop. Reseeding is also only a potential concern in the same season – seeds should not stay viable the following year.

If the crop is being grown as green manure, it’s commonly tilled in in the vegetative stage. In this situation, it can be left to flower a few days before tilling in, but can still be terminated before seed set.

Grass cover crops – such as small grains, ryegrasses, and perennial grasses – usually produce no nectar and not as much pollen as broadleaves (forbs like buckwheat or any legume). However, grown in a mix, these two types combine well. The flowering broadleaf species can attract insects, while the grasses perform many of the other cover crop functions that may be needed, such as nutrient scavenging and soil building.

Some mixes are planted at the borders or intercropped, not to draw beneficial predators but as a “trap crop” – to draw harmful pests out of the main crop. This should be a separate species that can provide an alternate host and reservoir for the pest. Also, these trap crops that support low levels of pests can provide an additional food source for beneficial insects. They may first elevate the populations of harmful insects, but the populations of predators will likely spike soon after in response.

Some Common Pollinator Crops and Their Side Benefits

Clover – can double as a palatable and protein rich forage. This includes Hubam Annual White Sweetclover, with higher nectar production than most other clovers. Its abundant blossoms produce nectar flow from morning through late afternoon, while it also builds soil fertility by fixing nitrogen.

Brassicas – also a potent biofumigant that naturally controls nematodes (break crop)

Cowpeas – in addition to the floral nectar production, cowpeas have extrafloral nectaries – nectar producing glands at the base of the leaf stem.

Buckwheat – grows faster than many summer annual weeds and forms a dense, shading, weed-suppressing canopy with its broadleaves.

Gotta Have Diversity

Mixes are more useful than straight stands in almost every way, but not least because they both provide bio-diversity and support it. By expanding plant species diversity just a little bit, we can greatly increase insect diversity. More species of insects means more natural checks and balances in the insect population, so no one species can predominate. This is the epitome of successful Integrated Pest Management (IPM) – and reduces the chances that a single species can decimate a crop. If a variety of blooming species can be incorporated, the combined effect of different bloom times will lengthen the overall blooming period.

In a straight cover crop stand, there will be only a short bloom period, which creates a feast-or-famine situation for bees. Mixing different species helps mitigate this shortage-vs-abundance spike.

While most common blooming cover crops are excellent for growing beneficial insect populations, native plants and wildflowers are optimal for permanent pollinator strips, and have been proven to attract more abundant and diverse pollinator groups.

Be a Steward of Diversity With Fewer Chemicals

Reducing insecticide use is a surefire way to boost beneficial insect populations. The stronger your IPM program – using break crops, trap crops, pollinators, soil building crops, and longer rotations – the less need you have for chemical control. It is a positive feedback loop, a situation that can only feed on itself for the better.

Avoid applying insecticides to flowering plants. Use chemicals with low residual times that do not accumulate in plants or soil. Systemic insecticides such as neonicotinoids have persistent chemical residues in soil and plant matter. These residues can persist for years and be reabsorbed later by crops that were not treated. Cover crops must be protected from insecticide drift.

Softening the Edge – A Haven for Creatures

Click for a tech sheet on what comes with the Summer Solar Panel Mix and more information about it.

Click for a tech sheet on what comes with the Summer Solar Panel Mix and more information about it.

Pollinator plantings also make great buffers and transitional zones. For example, planting corn or soybeans right up to the edge of a wooded area won’t be the best plan since the field edges will get shading from the trees and be vulnerable to wildlife living in the forest. A pollinator mix planted at the woodline eases this sharp transition and also helps draw beneficial insects out of the woods and into the field.

Summer Solar Mix is convenient in many rotations and scenarios. Consider the following request from a Western New York farmer:

“We are looking at possible cover crops to plant after the spring peas are harvested mid to late June prior to seeding winter wheat. Last year we had the opportunity to grow a crop of BMR sorghum sudan for a dairy operation after the peas (19.5 green chop tons per acre). Looking for other options if that opportunity is not available again.  Do you have any suggestions?”

Summer Panel Mix fits well in this particular situation as both a rapid soil builder and insect bio-diversity builder. It is appropriate here to plan it into the normal rotation for temporary farmscaping rather than placing it in a specially sanctioned area. Both can be done on the same farm, however.

This plan will be different on every farm, and each farmer is likely to know best where these plantings will offer the best fit and benefit to surrounding fields. The most important thing is to first have an understanding of the wealth of potential benefits, and the desire to take advantage of them.

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About the author

Genevieve provides forage and cover crop research and marketing support for King's AgriSeeds Inc. in Lancaster County, PA. She has also worked on organic vegetable farms and as an intern in agricultural field trials at the Rodale Institute.

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