Q. I have heard that after emerald ash borer moves through our area, it will be safe to plant ash trees again. Is this true?
A. Scientists do not yet have enough experience with the emerald ash borer to know what will happen over time to trees that survive the initial wave of the borer. Ash seedlings and saplings are common in forests, woodlots and rights of way; however, and it is unlikely the insect will ever completely disappear from an area. That means that ash trees may always be at some risk of being attacked by the borer but it seems reasonable to expect that treatment costs could eventually decrease as pest pressure declines after the borer wave has passed.
There is considerable research being conducted at land-grant colleges such as Purdue, Illinois, Michigan State and Ohio State on parasitic wasps and diseases that attack borer larvae. Just recently, a study conducted by scientists at the Morton Arboretum discovered a native parasitic wasp, which also attacks borer larvae. Homeowners will still need to continue to protect trees they want to save until further research is completed. Remember, excellent information is available at Purdue University’s emerald ash borer website. Just Google “emerald ash borer Purdue.”
Q. Someone told me recently that blue-to-purple petunias are less likely to be eaten by insects and rabbits. Is this true?
A. Recent research conducted by the USDA’s Agricultural Research Service reports that anthocyanins present in deep blues and purple petunias caused slower growth and death in corn earworm and cabbage worms. The anthocyanins are thought to slow the growth rate of insects that feed on plants and flowers that contain them. In experiments conducted at the National Center for Agricultural Utilization Research, corn earworm caterpillars that were forced to feed on the blue parts of petunia petals gained less weight than those that fed on the flower’s white areas. In addition, when anthocyanins were isolated from the petunias and fed to caterpillars, they slowed the larva’s growth. Cabbage worms that were fed diets consisting only of blue/purple petunias died at much higher rates compared with caterpillars that were fed the white portion of flower petals.
There is no research that I could find that supports the idea that rabbits will not eat blue or purple petunias as readily as other colors. There are only anecdotal reports from citizens that report this phenomenon. Sometimes rabbits will not eat plants that are more mature-preferring newly planted tender plants such as lettuce, verbena, pansy and, yes, petunias.
Exclusion is the best way to prevent damage from critters such as rabbits to plants in the garden and landscape. This means fencing for garden areas, or temporary fencing placed over tender flowers and veggies until they are more mature and less likely to be eaten.
The Scarecrow – a motion-activated device that fits on a water hose – can be an effective electronic fence to keep critters away from a particular area.
