January 15, 2011
By Jennifer Llewellyn
OMAFRA nursery crop specialist

jen llewellyn I am lucky to have attended some really good meetings and conferences this past fall. Some of the events were in the form of webinars. I want to share a few highlights of these educational events. We are fortunate to have so many good people working on ornamental nursery and landscape plants. Their enthusiasm and zest for new and improved ways of doing things should inspire us all.

Effective EAB techniques

I attended a webcast on Dec. 1, featuring Krista Ryall of the Canadian Forestry Service. She presented a sampling protocol that was developed to detect emerald ash borer (Agrilus planipennis) in ash trees.

For years, we have tried to detect emerald ash borer (EAB). And for years, we have failed. The reality is that an ash tree will show virtually no symptoms, and yet still be significantly infested, resulting in it sometimes dying suddenly the very next year.

So where on the tree do we look for larval galleries? How many samples do we take, and how big should the samples be? The research team took large, asymptomatic ash trees on the edge of infested areas. They cut them into small pieces, so they could transport them back to the lab. The pieces were carefully labelled, providing exact identification as to location on the tree from where the samples were taken. The researchers even labelled them as to north or south facing.  

Some interesting results were that of all the asymptomatic trees they sampled on the edge of known infested areas, 50 per cent were infested with EAB. The south aspect had slightly higher numbers of larval galleries. Open-grown trees that are ≥ 20 cm DBH were the most often infested. The highest proportion of larval galleries was found on branches from the mid-crown. After they dissected all of the branch samples, they found that most of the larval galleries were within the first 1.5 cm of the branch (nearest the trunk).  Because they dissected the complete tree, they were able to randomly choose branch samples and found that they had an 80 per cent chance of detecting EAB if they chose two branch samples per tree. They also determined that a branch diameter larger than 6 cm was needed to ensure the possibility of larval galleries.

The exciting thing is that this sampling method is being used, and is effective. If we can detect infested trees earlier, we will perhaps do a better job at slowing the spread of this devastating insect.   

Breeding for disease resistance

I had the opportunity to travel to New England for the IPPS Eastern region meeting in late September. IPPS is always an excellent meeting for networking with other growers, researchers and extension agents for nursery crops. There’s just no other conference like it. I had the good fortune to meet with researchers who are actively breeding ornamentals for improved pest resistance and other ornamental traits.  

During one session, I found out about Dr. Tom Molnar’s work at Rutgers University. His research team has several hundred crosses of ornamental filbert (hazel, Corylus avellana). These seedlings show resistance to the very serious disease, Eastern filbert blight (Anisogramma anomala). Currently available cultivars Contorta and Red Majestic are susceptible, though they are quite popular in the landscape. In addition to disease resistance, some of the improved seedlings are showing novel traits such as defoliating bark, contortedness and cutleaf morphology. The research team needs to do further evaluation of disease resistance and stability of novel ornamental traits before the new cultivars can be released commercially.

Improving spray application

Dr. Heping Zhu is an agricultural engineer who has been studying application technology in nursery crops with USDA/ARS in Ohio. He gave an excellent seminar at the IPPS Eastern Region in New England this past fall.

Dr. Heping’s team has been looking at various factors to improve spraying application precision and reducing drift. Dr. Heping designed and built intelligent sprayers.  These are one-of-a-kind variable rate sprayers with output governed by crop plant volumes to improve crop coverage, while reducing total spray volume. The result is a significant reduction in non-target spray application without compromising efficacy.

The research team was able to reduce spray volume by 50 per cent.  With the high cost of pest control products and concerns over the environment, this technology has the potential to revolutionize spraying in nursery crops.

Unfortunately, Dr. Heping’s lab was virtually destroyed when the research station was hit by a tornado back in September. The team is rebuilding and finding support to continue its important work. In the meantime, Dr. Zhu is presenting at the Ontario Fruit and Vegetable Convention on Feb. 23-24 at Brock University. 
Jennifer Llewellyn may be reached at 519-824-4120, ext. 52671, or by email jennifer.llewellyn@ontario.ca.