Should some Plants come with a Warning Label? November 2020
Yes, I wrote it. Should people be warned about plants that will be installed or exist in their landscapes that will REQUIRE pesticide use or extensive cultural controls to maintain their value as an aesthetic plant- their sole purpose. I’m not writing about pollinators, natives, butterfly attractants, food sources for man or beast, or another buzzword of the industry. This is plants that use space and resources, provide some sort of aesthetic appeal, in some cases have lore attached, are part of the everyday mainstream yard, venue, campus: any maintained space.
In my attempt to reduce (eliminate) pesticides in the landscape, now 13 years, I am building a list of “The Bane of my Existence”, plants that will require chemical intervention to serve their purpose in the aesthetic landscape.
BOXWOOD: Oh Boxwood, you come with your own society. You’ve been planted at Versailles, came into the USA through Shelter Island, NY. “The Manor” Three Centuries at a Slave Plantation on Long Island- Mac Griswold. 2013 - Great book.
“The first planting occurred about 1653 at Sylvester Manor on Shelter Island, the NW part of Long Island in New York, using boxwood brought over from Amsterdam.” * Boxwood Society Website
Even though we have Buxus sempervirens- “ American Boxwood”, it is not a native, it is a cultivar. It is a native to Southern Europe, Northern Africa, and Western Asia. FYI Buxus sempervirens ‘Suffruticosa’ is “English Boxwood”.
I see a lot of bees on Boxwood flowers, I admire the healthy plants and understand their uses: “Cloud plants”, **Deer Resistance, formal gardens, hedges, lots of formal little round balls, triangles or squares…I get it. The aesthetic value of healthy boxwood has not missed me. But what other value? Not native, supports bees when in flower but what other benefit are we receiving? Our plants must now serve purpose, support a bird, bee or microorganism- they are no longer allowed to just lounge around in the yard without some sort of rent due.
BUT… Healthy Boxwood? Is it possible without pesticides or is that a compromise designers, installers, owners, caretakers are willing to take on? Are the owners of the property aware of the future plans and costs associated with having Boxwood on their properties. If this were any other product this would need to be disclosed. “To maintain the aesthetic value to the property, these plants may require a series of pesticide applications, several times a year, for the duration of their time on said property. The approximate cost of these applications will be a minimum xx.” What happens if they can no longer afford these methods? Do they have a product that needs to be recalled? I’m just causing trouble and throwing it out there. Imagine it was any other purchase: would you back it?
Boxwood problems: For now…
References: Check these for Pesticide control information: Follow Labels
Cornell Branching Out and Insects that Feed on tree and shrubs, Cornell Recommends,
IPM Approach- U MD
Boxwood Leaf miner: Diptera: Monarthropalpus flavus: A fly- the larvae are maggots. Few parasites, not NO Parasites. They come when the leaf miner is in the leaf, about same time as systemic treatments so… “We target Beneficial timing”
BL: GDD_ 350-600, PPI Weigela: May to June- Adults. Orange mosquito like flies about 1/8 “ long, they form a ‘halo’ of flies around the plant when laying eggs, you’ll see them. GDD 1200-2400 GDD, PPI Abelia: Blister mines, Larvae feeding within leaves, they’re there for a year. This is the stage parasitic wasps attack the larvae, laying an egg inside each maggot.
Branching Out reported emergence of adults on May 20th, 2020. Vol 27, #4, Vol 27 # 10
Boxwood Mites: Eurytetranychus buxi: a Spider mite, feeds only on Boxwood. Adult mites are greenish brown and feed on the undersides of the leaves, a hand lens is needed. Few parasites, not NO Parasites. Again, we target the arrival of beneficial insects and arachnids. GDD: 245-600, PPI: Cercis, Chionanthus First two weeks of May. Japanese Boxwood seems to be less susceptible.
Branching out: Vol 27, #3
Boxwood Psyllid: Psylla buxi : Cupped leaves on Boxwood: This is NOT an ID feature: Ilex vs Buxus. It is insect damage. Psyllid nymphs are flattened with fluffy wax on their posterior. They feed on newly expanding leaves puncturing cells. As the healthy cells expand the damaged cells cause a cupping of the leaf. This cupping becomes a nice little habitat. ‘American’ boxwood has less severe damage. To prevent egg laying: GDD: 290-440 May, Laburnum, Ninebark Branching out: Vol 27, #2
Psyllid Branching Out: June Vol 27, # 5 Adults emerging in NYC Area. Light green and can be seen jumping around the foliage. I generation per year, mating occurs, females lay eggs. “This is an aesthetic problem and treatment is not usually necessary”. Branching Out. I have found winter pruning to be effective. I lay tarps under the plants to catch cut leaves and give those shrubs a good hard shake. This is true with many insects, maybe I’ll cover at another time.
In a Special Pull Out Article from Branching Out: Vol 27 #6 – This can’t be Good…
Boxwood Tree Moth/ Caterpillar: Cydalima perspectalis: Lepidopterus ( Bt?):
No preferred host. Referred in Europe as “Horticultural pest or Environmental Disaster” Began 2007, Netherlands and Germany, 2015 Outbreaks in London, 2018 Canada. “Slowly I turn, step by step, inch by inch…” an old Vaudeville skit, now refers to the words “Box Tree moth”.
The moths are distinctive: Seen around boxwood, White wings with dark edges, and a white spot. There is also a white form, key: they fly around boxwood. Nocturnal creatures. The caterpillar is Bright green with black and yellow stripes.
** Box Webworm is a Grey caterpillar without green and mainly causes webbing, not defoliation like the BTM. (will not be expanded on in this article)
Lures are available for the male BTM Pest. It would be best NOT To call them “Just for curiosity”. New lures are being developed to capture both male and female, but unless you suspect you have a problem, don’t create one.
Volutella Canker: Fusarium spp: Volutella buxi: Cornell
Pseudonectria rouselliana: U MD
Before new growth in spring, leaves of the tips of infected branches turn red, then bronze, then yellow. Infected branches die back. Loose bark and girdling are evident on dead stems. In moist weather the fungus appears as salmon colored fruiting bodies on leaves and stems. Most buxus are susceptible. Air circulation, dead leaf management, pruning, alleviating stresses can help.
*** NOTE: I had always learned that Sweet box, Pachysandra and Box can share Volutella but as DNA and further research categorize our world even more, I am finding a lot of conflicting or new information. Some sites use a general term: Volutella and Yes, it affects all three. I will research further.
And Boxwood Blight: I listed this LAST as this is not my biggest problem. I have submitted numerous samples and Blight has never been in issue. I know it exists but so far, not in my world. Calonectria pseudonavicultata. Associated with rainy weather in late summer or fall. I am not tgoing to write all the information here: see; the Boxwood Society website, Boxwood growers, Cornell Branching Out : Vol 27 #6 for the latest updates.
There are more, not of significance at this time: about 20 scale insects, erinium mite, western European psyllid, yellow necked caterpillar and Boxwood webworm, as named in Branching Out Insert Vol 27 # 6
So as you plan for this new season, designs being created, equipment getting ready to dig, tools being prepared, materials ordered- consider the long term results of the plan. We’ve seen how much can change in one short year. The world, not a foreign place or people have been brought together to take a HAR D look at what we’re doing as humans and as people. This can translate to the smallest task of taking things forward.
Our lives have come with a warning label, how long before we take heed? Just a thought, an idea, a fleeting notion- can we do better? And how?