Medlock Ames – Enhancing Beneficial Insect Habitat With Flowering Cover Crops

Company Summary:

Medlock Ames is a values-driven company dedicated to preserving our land and treating all with respect while maintaining the highest standards. We are an organic vineyard and winery committed to farming in harmony with nature and crafting wines that represent our beautiful surroundings.

Executive Summary:

Insect pests such as Vine Mealy Bug, Three-Cornered Alfalfa Hopper, and Leafhoppers can cause economic losses in vineyards if not adequately controlled. Some pesticides can have adverse effects on the environment and worker health, and their use may be prohibited under organic certification. Furthermore, pesticides can be toxic to insect predators of vineyard pests, and their use can exacerbate pest outbreaks. Enhancing habitat for beneficial insects that prey on vineyard pests, by planting flowering cover crops and eliminating pesticides can control vineyard pests in a way that is better for the environment and for worker health.

Reason Why/Motivation/Background:

In general insect pests are not a serious concern for us in our growing region. They generally are not present in high enough populations to cause economic loss. We feel that planting flowering cover crops is a good strategy for managing pests, but our true motivation with this practice is to create better working conditions for our vineyard employees. Leafhoppers can cause economic damage in high numbers, but our real concern is that they jump off the grape leaves and into the face of our vineyard team. It is very annoying and distracting to them. Using chemicals to manage the problem is contrary to our belief. Flowering cover crops is the best solution for us.

Project Description:

One of the reasons that conventional, chemically-based farming is ultimately unsuccessful or becomes uneconomical over time is because the chemicals that kill pests also kill natural predators of those pests. Once the natural predator population is wiped out, there is nothing to control the pests. The pests that do remain reproduce and pass on their resistance. Some insect pests have multiple generations per year giving them many opportunities to evolve. Higher rates and more frequent applications of pesticides are needed to achieve the same level of control, until it’s too expensive and too toxic for the farmer and the land.  The long-term effect of these chemicals is loss of biodiversity and the compromised health of the people who work the land.

In our vineyard, we use a much more effective system, one that has been product tested for hundreds of millions of years. We plant a broad array of flowering plants, such as Sweet Alyssum, Purple Tansy, Crimson Clover, Giant Larkspur, Butterfly Bush, Linheimer’s Bee Blossom, Aster, Lanceleaf Coreopsis, Sweet William, Perennial Lupine, Siberian Wallflower, Blanketflower, Purple Coneflower, Mexican Hat, Yellow Prairie Coneflower, Shasta Daisy, Blue Flax, Four O’Clock, Russell Lupine, Black-Eyed Susan, Missouri Primrose, Columbine, Foxglove, Dense Blazing Star, Flashy Evening Primrose, Moss Verbena, White Yarrow, and Queen Anne’s Lace, both in dedicated garden beds and in the space between rows of grapevines. These carefully selected flowers attract beneficial insects. The adults of these insect species rely on flower nectar as their food source. This is particularly important in the driest part of the late summer when there are not a lot of wildflowers in bloom. The adult insects feed on the nectar of the flowers and then fly around the vineyard looking for vine pests such as leafhoppers, vine mealybugs, and three-cornered alfalfa hoppers. These beneficial insects, such as hoverflies, minute pirate bugs, ladybugs, and parasitoid wasps are harmless to humans, but they are very effective at controlling pests.

It’s possible to buy and release the beneficial insects into the vineyard, but it is expensive to do on a large scale and if conditions are too hot, too cold, or not enough flowers, the insects will fly away or die. A better solution is to create a habitat that encourages the insects to thrive, one with no insecticides and a broad array of flowers that bloom throughout the year. If you build it, they will come.

The beneficial insects won’t kill all the pests, and that’s not really the goal. We want a healthy balance of predator and prey. That ensures that there is always a large population of beneficials so that an outbreak of pests never happens.

In our vineyard blocks, we normally plant cover crops in every row or every other row. This is typically a blend of grasses to provide quick germination to prevent soil erosion from autumn rain as well as legumes for their ability to add Nitrogen to the soil. Every fifty feet we plant an insectary row with a mix of 15-20 flowering plants. This spacing is ideal as the beneficial insects we hope to attract are only able to fly 25 feet, so a planting density of 50 feet allows coverage throughout the entire vineyard.

Benefits/Achievements:

We have not quantified the impact, but anecdotally we see lots of activity of our desired beneficial insects flying around these flowering plants.

Lessons Learned:

The insectary rows should be mowed high soon after bud break. This will knock back the resident vegetation which typically has many tall grasses. The mowing will allow more light onto the flowering plants and will help them grow more quickly. For maximum effect, it is important to wait until the plants finish flowering. Waiting until the plants go to seed will help to establish the flowering cover crops for the following year as well. Seeding at a rate of 20 lbs per acre is ideal. Planting into a prepared seedbed works best, but under no-till conditions, it is also possible to lightly pass a disc over the permanent cover prior to seeding.

Next Steps:

Our next step is to work with an entomologist to set up traps so that we can monitor and quantify the activity of our desired beneficial insects and possibly determine the extent to which they are parasitizing the vineyard pests we hope to control. We would also want to do trapping and monitoring in areas where we are not

Potential For Replication:

This practice has great potential for replication. Most vineyards in our region regularly plant cover crops in the Fall. While the flower seed is more expensive than more common grass/legume mix cover crops, the seeding rate is much lower and they only need to be seeded every 50 feet so it does not require a significant cost increase.