Research on ways to eradicate the emerald ash borer (EAB) is beginning to yield some interesting results. We already have effective chemical controls, such as the Tree-Age that we inject into trees. This product is most effective when applied as a preventive before a tree is infected. However, it can also be used as an insecticide with satisfactory results after the EAB has attacked a tree.
A recent posting on Entomology Today’s website tell of research into why Asian ash trees are able to fend off attacks while North American trees cannot. Researchers found that the Asian species have a set of genes that are not present in the North American species. Scientists at The Ohio State University have launched a crowd funded project to identify the genes that allow Asian ash trees to resist EAB attacks.
Meanwhile, researchers are working on ways to cross breed our North American ash trees with the resistant Asian ash trees. This will give the landscape industry ash trees that are resistant to this pest.
This cross breeding technique is also being used among elm tree breeders. They are crossing American elm with foreign species that are resistant to Dutch elm disease (DED). The desired result is a tree that has the unique form of an American elm but is resistant to DED. These breeding programs are yielding mixed results.
If the ash cross breeding programs yield good results, we will have ash trees that have the stately appearance of a native species but are resistant to this devastating insect.
If the specific Asian gene set can be isolated, it is conceivable that cross breeding could then by replaced by introducing the Asian genes into the native species in the laboratory or nursery where trees are propagated.
Successful cross breeding is a number of years off. The first cross bred trees have just been planted. So, there will be a lengthy trial process before they can be released to the nursery industry. I believe isolating the gene set and inoculating these genes into seeds or tissue culture in the laboratory is a really long way off.
This means that we still need to be vigilant about continuing to treat the ash trees we already to have to minimize the number attacked by the emerald ash borer, and those that succumb to this pest.