Let's visit some horticulture research labs this
week to see what plant scientists are finding to help us garden better.
* Plants Can Smell?
They may not have noses, but apparently plants can pick up scents.
Researchers at Penn State University have documented that goldenrod plants, when exposed to a male fruit-fly mating attractant, activate chemical defenses that guard against fruit-fly egg-laying damage.
Penn State entolomologist Mark Mescher says researchers already knew that plants often kick into defense mode by picking up minute odor changes from insect-damaged neighbor plants.
"What's new about this," he says, "is that it seems that plants may sometimes be able to smell the insects themselves."
The research team isn't sure exactly how goldenrod's olfactory system works, but the findings could lead to new avenues to head off bug damage.
* New Crabgrass Weapon?
Organic gardeners currently don't have a good way to kill and prevent pesky crabgrass in the lawn.
Researchers at the U.S. Department of Agriculture believe they may have found a promising "green" solution in manuka oil – an essential oil distilled from the manuka tree, a shrubby species native to New Zealand and Australia.
USDA scientist Dr. Franck Dayan found that this oil both reduces crabgrass by 94 percent and reduces its germination by 50 to 90 percent in the first place.
Field tests in Mississippi also found it was effective against velvetleaf, pigweed and several other weeds, especially when combined with lemongrass oil.
Several more years of testing are needed to
determine if manuka oil will make a viable new organic weed-killer and weed-preventer.
* Going After Stink Bugs
We got a bit of a break last year from that recent stinky import – the brown marmorated stink bug – but University of Maryland entomologist Michael Raupp (for one) is forecasting a rebound this year.
USDA researchers are on the verge of zeroing in on a more targeted scent attractant that will make stink-bug traps more effective.
A team at USDA's Beltsville, Md., laboratory have been comparing different formulas of a scent released by male stink bugs and believe they've found a good one that's also easy to manufacture. The formula seems to be especially effective in early spring when new populations are just getting started.
Other researchers are mapping the stink bug's genes and studying imported wasps that keep the stink-bug population under control in Asia.
If the studies pan out, we should be able to minimize this double-trouble bug that both destroys crops and invades our homes in winter.
* Keeping Out New Invasives
Some of our worst weeds originally came to the United States as imported landscape plants, a result of fairly lax rules on what can come in and what can't.
Researchers at the universities of Georgia and California have come up with a possible better way to deal with future introductions – a system that predicts the likelihood of a plant becoming an invader.
The researchers found that just four traits give a surprisingly accurate weedy predictor – medium seed size, high genetic chromosome counts, an ability to tolerate both wetland and upland habitats, and a large native range.
By rating plants on those four factors, Georgia scientist John Drake says it would be possible to "draw a line in the sand" and rule out the riskiest future imports.
He estimates that only 15 percent of
potential introductions would cross the line, and he adds that about a third of
our worst weeds could've been screened out by the proposed system.
* Trees for Health?
It may not mean that losing trees directly causes our health to go downhill, but a new study from the U.S. Forest Service shows an intriguing connection.
Researchers looked at 18 years of data from hundreds of counties in 15 states and found 21,000 more deaths from heart and lung diseases in areas where the emerald ash borer had been wiping out trees.
Lead research forester Geoffrey Donovan said the higher death rate held despite accounting for differences such as income, race and education.
Says Donovan: "There's a natural tendency to see our findings and conclude that, surely, the higher mortality rates are because of some confounding variable, like income or education, and not the loss of trees. But we saw the same pattern repeated over and over in counties with very different demographic makeups."
The researchers didn't delve into possible reasons for the association, but numerous other studies have found both mental and physical connections between plants and human health.