IPM Sometimes Means Soil Improvement

You usually get an insect article from me, but this time I am expanding my outreach about research we’ve conducted for the last 3 years, studying soil improvement to increase plant vigor. We obtained a three-year SARE grant to work with nurseries to modify soil structure and increase the number of beneficial organisms. The information obtained from these field trials should useful to cut flower growers.

One plant that performed well in our trials is daikon radish. These can grow a leafy top as tall as two feet, as well as a root (similar to a carrot but larger) as deep as 24 inches. Forage daikon radishes are in the Brassica family and have as good or better protein and mineral content as other members of that family, including turnips and rape.  The deep root radishes build organic matter and increase nutrient content in the root zone. In early spring, the underground shoots rapidly decompose, creating voids which aerate the soil. At the same time, the decomposing shoots provide new organic matter for your cut flower plots. The third thing forage daikon radishes do to improve the soil is to reach down and pull nutrients from deep underground and use them in the development of the shoot which decomposes later in the spring.

Cut flower growers can plant forage daikon radishes by themselves (10 pounds per acre recommended planting rate) planted at a depth of ¼ – ½ inches deep. Just make sure you sow seed at least 6 weeks before the first frost in your area to give them adequate time for development before cool weather hits. We found it best to seed in September in Maryland. With the first very cold weather, usually in December, plants will die and the large root will decompose, adding organic material to the soil. The flowers will help attract beneficial organisms that like to feed on pollen.

Seed is relatively cheap. We kept seed for use over the three-year project and the seed we bought the first of the trial was still viable after three years. Plants come up very rapidly after a couple of rains, usually in ten days to two weeks.

Like all other brassica (with the exception of hybrids like T-Raptor), it is recommended that you do not plant forage daikon radishes in the same plot every year to avoid potential long-term fungus problems. Simply rotate areas each year, and sow them every other year in a given plot. They do not do well in wet sites. Avoid areas that stay too wet all winter long or you will get little to no growth.

If you try this out give me feedback on how well this works at your operation.

Burn It Where You Buy It

Anyone seen those large purple triangles hanging in trees near roadways in the Midwest and East Coast?  We are getting lots of questions about these structures. They’re glue-smeared traps to detect an invasive beetle from Asia that’s devastating ash trees in Indiana, Michigan, Ohio, Pennsylvania, West Virginia, Virginia and Maryland. The emerald ash borer has killed billions of ash trees across the United States since showing up in wood-packing material in Michigan in 2002, and in nursery trees shipped to Maryland a year later.

Federal and state governments have rallied to save the popular tree, commonly used in landscaping, for tool handles, flooring and baseball bats. More than 61,000 of the purple prism-shaped traps have been deployed across the country. About 2,600 of them were placed in my home state of Maryland in 2011. This is the time when traps are deployed because the borers tend to emerge from where they hatched and fly to other trees to mate and lay eggs in new ash trees.

The purple color attracts borers, and the traps’ appeal is magnified by a bait suspended inside which emits a smell similar to a wounded ash tree.

The traps by themselves can’t catch enough beetles to stop them. So USDA experts have imported three different species of non-stinging wasps from China, where they are natural predators of the ash borers. The wasps, which pose no risks to other species, have been released in seven states among beetle-infested trees, where they kill borer eggs and larvae. First released last year, the wasps seem to have survived the winter.

Encouraging as that may be, there’s still something important the public can do to help slow the spread of this pest: burn only local firewood. One of the main methods for transmitting ash borers, according to the USDA, has been moving firewood—often ash—from one place to another.

With camping season kicking into high summer gear, officials are urging campers not to haul wood with them but to gather or buy it where they stay. “Burn it where you buy it.” is the slogan.

Good advice, but you have to wonder if the wood you can buy at the big box stores or supermarket is really local. Perhaps there ought to be a law, or some kind of borer-free certification required? In the meantime, check the label of any firewood bundles you buy, or ask the seller where it comes from. And demand that only local wood be sold. That’ll be good for local suppliers and good for your ash trees, too.

Stanton Gill

Extension Specialist

Stanton Gill is an extension specialist (professor-ranked principal agent) in IPM and entomology with the University of Maryland Extension, based at the Central Maryland Research and Education Center in Ellicott City. He is also a professor in the Landscape Technology Program at the Germantown Campus of Montgomery College. Contact him at [email protected]