“The nitrogen in dog urine would seem to be a helpful fertilizer. In fact, the concentration of ammonium is often toxic to plants. ‘If you get one of these trees that every dog has to pee on, they can actually burn the bark,’ said Nina Bassuk, program leader of the Urban Horticulture Institute at Cornell University.
“Exactly how many dogs does it take to kill a tree? ‘That’s something that hasn’t been studied,’ Dr. Bassuk said. ‘And I’m not going to do it.'”
“Nina Bassuk, program leader of the Urban Horticulture Institute at Cornell University, says gardeners should make sure that their hellstrip planting doesn’t interfere with established trees. Trees play an important role in urban areas, she says, for providing shade, mitigating stormwater runoff, and helping improve air quality. So be careful when shoveling near root systems.”
It may feel like the Northeast gardening season is wrapping up. But your basil and tomatoes in particular need on-going vigilance because they are vulnerable to potentially devastating diseases, says Meg McGrath, plant pathologist at Cornell University’s Long Island Horticultural Research and Extension Center, Riverhead, N.Y.
Disease risk is increasing as the very hot, dry conditions of this summer shift to cooler, moister conditions with more frequent rain and long dew periods – all favorable for disease development, she explains.
Basil is at risk of attack from basil downy mildew, a new disease first seen in the U.S. in 2007 that has spread quickly in late summer each of the last two seasons in the Northeast. Sightings of this disease at the same time again this season suggests that, basil downy mildew is now a routine problem.
The first symptom that gardeners or growers are likely to spot is a slight yellowing on the upper surface of the leaves. Turning affected leaves over will reveal a grayish-purple (sometimes almost black) dusty growth which is the pathogen’s spores. Removing individual affected leaves won’t stop the disease, since the spores are easily moved on air currents.
McGrath suggests dropping everything when you first discover the disease on your plants, harvesting healthy-looking leaves, and preserving them as you usually would (by drying, freezing, making pesto, etc.) so you will have basil to enjoy later.
Late blight lesion on tomato leaf. Click for larger view.
Tomatoes are at risk from attack by late blight (as well as other diseases). While late blight hasn’t been nearly as common as it was in 2009, it has been confirmed in at least 8 counties in New York. (See the Late Blight Alert blog.) McGrath recommends inspecting plants at least once a week – more often if weather is cool and wet or humid. Immediately remove and bag foliage you suspect might be infected.
While late blight symptoms are distinctive – dark brown lesions on stems and leaves with white fungal-like growth developing under moist conditions – it’s possible to confuse it with other diseases. See Late blight ‘imitators’ to help distinguish late blight from other diseases. Your local Cooperative Extension office can help you with identification.
For steps you can take to avoid late blight and what to do if your tomatoes get it, see Avoid the late blight blues. (Because the disease is so contagious, it’s often better to be safe than sorry and remove and properly dispose of plants suspected to be infected.)
Questions or to be notified of next course, email the instructor, Marguerite Wells: email@example.com
This course will increase your enjoyment and success making new plants through:
Plant Propagation goes well beyond the basics to deliver both the art and science of plant propagation. Participants will examine in-depth the biology, anatomy, history, and use of these propagation techniques. We send students a complete kit for home propagation, including propagating flats, seed, and live cuttings.
The Department of Horticulture Seminar Series resumes for the fall semester Monday, Aug. 30 at 3:30 p.m. in Plant Sciences Building Room 404. (Pending approval of students taking the course for credit, the time may move to 4 to 5 p.m. after the first seminar.)
Tentative schedule for September:
August 30: The New Merged Horticulture Department: A Question and Answer Series
Marvin Pritts and Susan Brown, Department of Horticulture, Cornell University
Sept 6: Labor Day Holiday (no seminar)
Sept. 13: Title – TBA
Rebecca Schnelle, Robert Langhans Visiting Scholar, Department of Horticulture, University of Kentucky
Sept. 20: Horticulture in a Changing Climate
David Wolfe, Department of Horticulture, Cornell University
The rest of the fall line up is coming soon. Check the seminar website for updates.
Willowpedia is a new website focusing on the study and commercial use of shrub willows as a sustainable feedstock crop for bioenergy, biofuels, and bioproducts, as well as for environmental engineering and horticultural applications.
Shrub willows (Salix species that grow 15 to 25 feet tall) are ideally suited for bioenergy plantings on marginal farmland, particularly on soils where poor drainage makes planting agronomic crops difficult. Plantations are usually established by planting dormant stem cuttings or whips, available in New York from Double A Willow nursery. The multiple stems from each shrub can be harvested every three or four years for the life of the planting, usually 25 years or more.
Larry Smart, associate professor in Cornell University’s Department of Horticulture based at the New York State Agricultural Experiment Station in Geneva, has spearheaded the site’s development, which was initiated by Chris Cooley of CMC Creative Design and completed by Roxanne Li (’12) as a part of her internship funded by Cornell Cooperative Extension. The site currently focuses on Smart’s work and collaborations with researchers in Cornell’s Departments of Entomology, Plant Pathology and Plant-Microbe Biology, and Biological and Environmental Engineering. But Smart hopes that the site will grow to become a center for the global exchange of knowledge among the entire willow community and the public.
From an article Sustainability at Mann’s door by Eveline Ferretti on the Mann Library news site about the garden at the library’s entrance, one of 175 projects accepted in the pilot phase of the Sustainable Sites Initiative that will test the rating system for green gardens and landscapes:
“The Mann entrance garden is the newest installation realized by students of LA/HORT 4910/12 (aka ‘Creating the Urban Eden’) under the tutelage of horticulture professor Nina Bassuk and landscape architecture professor Peter Trowbridge. On August 4, a tour of the garden led by Fred Cowett (Dept. of Horticulture) and Addy Smith-Reiman (Landscape Architecture / City & Regional Planning) highlighted another major feature of the garden: Its status as a pilot project for the a national-level Sustainable Sites Initiative that aims to promote greater sustainability in the design, management and maintenance of landscapes and gardens across the U.S.”
“Cornell University has chosen East Rockaway in Nassau County to train students in doing a village-wide street tree inventory. On Saturday, August 7 and Sunday August 8, five teams, headed by Professor Nina Bassuk (right) of the Cornell University Urban Horticulture Institute, will be collecting data on village street trees. Other members of the teams will be local high school and Girl Scout youth and members of the Village Tree Advisory Board.”
The article goes on to point out the importance of street trees and how inventorying them can help identify species that are adaptable to climate change and hotter, drier conditions.
With the help of a Dreer Award, Erin Marteal (’10 MPS Public Garden Leadership) is embarking on ” … a profound journey of discovery.”
Her mission? “To make heads and tails of permaculture, perceptions of permaculture, and how permaculture addresses the educational missions of public gardens across the globe.”
For the next six months, she traveling to Australia (New South Whales, Victoria and Tasmania), New Zealand (North and South Islands) and South Africa (Durban and Cape Town) with the primary focus of bridging permaculture into public garden education.
If you’d like to keep up with Erin’s travels — both geographical and intellectual — check out her blog, Permaculture in Public Gardens. Even though she hasn’t left the U.S. yet, she’s already started bloggin, including her visit to the Permasphere, the Los Angeles Arboretum’s Permaculture garden while attending American Horticultural Society’s Children & Youth Garden Symposium in Pasadena last month.