Announcements

Job offersmore »

Tweeting Growers

Last commentsmore »

Top 5 - yesterday

Top 5 - last week

Top 5 - last month

Exchange ratesmore »




US: Looking outside of the box for Boxwood Blight solutions

Boxwood blight (BB) continues to spread throughout the US. The University of Illinois Plant Clinic recently announced its presence in Illinois. The clinic received two boxwood samples late 2016. Both were from northeast Illinois and were collected from recent landscape installations. USDA APHIS confirmed that both tested positive for BB. University of Illinois Extension personnel are confident that the infected plants did not likely originate from an Illinois nursery.



First identified in the US in the fall of 2011, BB has since been detected in at least 22 states across the US, in both nursery and landscape settings. Two closely related fungi, Calonectria pseudonaviculata and C. henricotiae, cause boxwood blight on three plants: boxwood (Buxus), Pachysandra, and sweet box (Sarcococca).



The Horticultural Research Institute continues to monitor, support, and communicate BB research activities to the industry. Research activities have been heavily focused on management measures:

Sanitation and disinfection
Sanitation and disinfection are two critical components of all disease control programs. Soil in nursery beds and benches can harbor BB microsclerotia, overwintering structures in dead leaves that will be viable for years. Several commercially available sanitizers, such as ethanol and bleach, were evaluated for their efficacy against microsclerotia in lab studies. Ethanol was very effective in Dr. Nina Shishkoff’s (USDA-ARS) trials and completely killed conidia in leaf debris in studies conducted by Norm Dart, VT. Studies at CAES have shown bleach to be effective against BB spores as well.



Mulching
Mulching can either help or hinder development of a plant disease, depending on the system. When it comes to BB, mulch theoretically should reduce disease development by reducing pathogen dispersal via rain splash (a primary cause of BB spread). Researchers at VT are investigating the potential mitigation of BB using various mulches. Studies are being conducted in operational nurseries and residential landscapes to best gauge impact on disease development.



Fungicides
Few data exist on what fungicides best control BB. Dr. Jim LaMondia at CAES is comparing commercially available products and has identified some that are effective. A number of products were highlighted for their control activity, including pyraclostrobin and propiconazole. Both products have demonstrated good preventive control. Propiconazole, in particular, shows promise for early curative control. In fact, most triazole fungicides (also known as DMI’s) control BB preventively, as does preventive sprays of chlorothalonil. Always consult current product labels before applications.



Biological control
Dr. JoAnne Crouch, USDA-ARS, and Dr. Chuan Hong, VT, are screening large numbers of microorganisms in the hopes of finding candidates for biological control of BB. Endophytes, microorganisms that live in or on a plant without causing disease, have been identified associated with boxwood leaves and roots. Often biological control agents have complex interactions with plants; so, this work can be tedious and time consuming.



Heat therapy
Thermal inactivation, or heat therapy, has been used successfully in the past to eliminate pathogens from woody propagated plant tissue. Dr. Marc Cubeta’s lab at NCSU is conducting experiments to examine the response of C. pseudonaviculata and boxwood varieties to treatment with hot water to manage BB during propagation. After exposure to hot water at 47.5 °C (117.5°F), conidia are either killed or impaired in their ability to cause infection. Preliminary results suggest that certain boxwood varieties are still able to root after exposure to these temperatures. Several varieties are being screened, and studies are ongoing to determine whether the pathogen can be eliminated from infected cuttings in this manner.



A breeding program to identify disease resistant varieties and exploration into fungicide sensitivity are two other key components of this collaboration.

AmericanHort and its research affiliate, the Horticultural Research Institute, supported funding of this research through the Farm Bill Section 10007. This collaboration is coordinated by the IR-4 Program, a USDA-sponsored entity to increase the specialty crop industry’s access to labeled pest management products.

For more information 
Horticulture Research Institute 
Jennifer Gray 
T: 614.884.1155


Publication date: 1/27/2017

 


 

Other news in this sector:

8/16/2017 Royal FloraHolland sounds out clients on image auctioning
8/15/2017 Register now for Biobest Day in the Rockies
8/15/2017 International collaboration on crop protection
8/15/2017 Common root diseases of Chrysanthemums
8/14/2017 New Pest Management Guide available
8/14/2017 "Bayer portfolio serves needs of greenhouse and nursery growers"
8/11/2017 CAN (ON): Best management practices for outdoor mum, hydrangea growers
8/11/2017 US: "Good-guy" fungus to take on killer of oaks and ornamental crops
8/10/2017 NL: Combat PlamV with UV in the lily crop
8/9/2017 US (OR): Farwest speakers deliver talks on pest management
8/8/2017 UK: Garden retailers sign up to industry Xylella statement
8/7/2017 Asperello T34 Biocontrol wins Silver Award at Salon du Végétal
7/21/2017 Broad mites in ornamental crops: Scouting and sampling
7/21/2017 Urban horticulturists see the benefits of mycorrhizal fungi
7/20/2017 UK businesses hope to avert xylella fastidiosa threat
7/20/2017 Broad mites in ornamental crops: Challenges and treatments
7/14/2017 Biobest launches Bluestim in the USA
7/13/2017 Parasitizing wasps offer hope against devastating lily beetle
7/10/2017 Xylella fastidiosa arrives in the Iberian Peninsula
7/10/2017 UK: New plant protection products identified to help ornamental growers

 

Leave a comment: (max. 500 characters)

  1. All comments which are not related to the article contents will be removed.
  2. All comments with non-related commercial content, will be removed.
  3. All comments with offensive language, will be removed.




  Display email address

  new code