June 2021 — Volume 11, No. 6
Hello Everyone,
This is the busiest time of year in the garden, and 2021 is no exception. Soil and air temperatures are warm enough now to plant anything, hardy or tender. Rainfall for May was under the norm until Memorial Day weekend when the usual 4.4” for the month was finally reached. Don’t stop watering your new plants - see our summer watering instructions below.

We started our compost tea routes in mid-May when the soil temperatures warmed up. These applications are timed to the periods of highest biological activity in the soil. Reese has also been busy with spot spraying the emerging pests and keeping up with tick and mosquito spray routes.
Rebecca Zhang, Marketing Intern
In this issue, we’ll give you an overview of what our crews have been doing lately. Our new marketing intern, Rebecca Zhang, is soon to be a senior at Mt. Holyoke College. She has been out and about to photograph our crews in action and then to write posts and captions. We are enjoying her energy and creativity!

Here she is on Linkedin.
Look What We’ve Been Doing!
Image of PBOG worker, Susan, mulching
Susan carefully spreads mulch around woodland garden plants
Images of Edible garden
Planting a new edible garden incorporating woody and perennial plants occupied our project crew for two weeks
Image of Priscilla filling gaps in border
Priscilla lays out new perennials to fill gaps in a long perennial border
Image of PBOG workers Coleman and Erica setting up fencing
Erica (right) and Coleman (left) constructed a fencing system and built naturally mounded raised beds for this vegetable and cutting flower garden
Natural Control of Japanese Knotweed
Image of Japanese Knotweed in sprouting in Spring
Japanese knotweed in Spring
Sometimes nature comes a little too close when there is disturbed ground. One of the common invaders is Japanese knotweed. This shrubby plant in the knotweed or buckwheat family was imported in the late 1800s as an ornamental curiosity and became a rampant escapee in our area. You may have seen it lining roadsides or stream banks. It spreads by both seed and runners. Therefore, it is important to never let the plant flower. Attempting to dig it out is futile since the roots go down several feet.
At PBOG, we are controlling this plant weekly in our own nursery area in Ayer. A large stand had been allowed to grow over time unchecked at the edge of our space. We find the most effective way to weaken the plant over a period of several years is to repeatedly cut the stems once the plant reaches 6” in height. Cuttings are then dried out on a pallet and composted once they lose their biomass.
If you have knotweed stems sprouting in your garden, adopt this practice. Then plant a native tree or shrub to shade out the knotweed, since this plant prefers full sun. We like to use Aesculus parviflorus, Bottlebrush Buckeye, for this purpose. This native shrub is fast-growing, broad spreading, and has large leaves that will shade out the weakening knotweed plants.
Image of Japanese Knotweed in flower
Japanese knotweed in flower
An alternative natural control method for Japanese knotweed is to inject the stems with an undiluted solution of 30% horticultural vinegar. This is rather more time-consuming but effective.

Please let us know if we can help you start managing your Japanese knotweed this season!
Image of Japanese knotweed in Summer
Japanese knotweed in Summer
We love warm weather - but it brings out three key insect pests!
Did you know that when the soil or air reaches certain temperatures, this triggers egg hatch on many insect pest species? Damaging larvae emerge to feed on our plants.
Image of white cottony ovisacs
White cottony ovisacs
Cottony camellia scale is a soft white scale that sucks sap from the leaves of many common landscape plants. Although it is most often seen on hollies, it can also be found on camellia, yew, euonymus, maple, English ivy, hydrangea, and rhododendron.
Scale will excrete “honeydew," a sticky substance that attracts stinging insects and creates optimal conditions for black sooty mold. Sooty mold will cover the leaves making it difficult for the plant to photosynthesize.
Image of leaf damage
Example of Sooty Mold
Adult females are about 1/8 inch long, oval and tan in color with a brown outline. They lay white cottony ovisacs containing hundreds of eggs on the undersides of leaves in May. Throughout June the eggs emerge into crawlers. Scale crawlers will be about the size of a mite and amber in color. This period is the only mobile stage in the insect's life and is also when the insect is most vulnerable since it has not yet developed a hard outer shell.

Timing is everything, and for this reason, we like to spray an organic insecticide, Aza-Direct® exactly at this time in the lifecycle. Pruning out severely diseased branches can also increase air circulation and create conditions that do not favor sooty mold development. Adjusting the soil pH and soil microbiology through amendments can also go a long way in restoring balance.

It may take several seasons to completely control a scale infestation. In severe cases, we will recommend removing the plant. But with a continued treatment plan of proper soil pH, developing microbiology, pruning, and organic insecticide, over time the health of the plant can be restored.
Roseslug sawfly
Rose slug sawfly will be out any day now. From a distance you may notice dingy brown or grey leaves or even skeletonized ones. A small worm will be on the underside - the slug sawfly. Luckily, there is just one generation of this pest per year in our area. We spray our Neem oil product if we see the pest. To help your rose push out new green leaves, we recommend liquid organic foliar feeds weekly or as often as you can manage! Rake up dropped leaves or prune off damaged leaves as appropriate.
Boxwood psyllid shows up on the new growth tips in late spring where eggs overwintered on bud scales. You’ll see curled, cupped margins. Living inside is the immature nymph, sucking sap from the leaves. Eventually, there will be discoloring from green to yellow. This impacts appearance of your boxwood, but not its overall health. We can control boxwood psyllid with insecticidal soap or summer-grade horticultural oil. In many cases, the cupping will be pruned away once new growth has hardened off at the end of June.
Images of Boxwood pysllid
Boxwood pysllid
Image of leaves damaged by Boxwood leafminer
Leaf damage by Boxwood leafminer
More damaging is Boxwood leafminer, which this year coated boxwood leaves with clouds of whiteflies in late May. Leaf blistering and discoloration will follow in June. We turn to the same organic insecticides to control this pest. Multiple applications may be necessary.
We recommend a thinning style of pruning for these shrubs. Site them away from buildings when possible to allow for best air circulation. Soil testing, amending, compost topdressing, and our compost tea program also help keep boxwoods healthy!
Plant Pick: Cornus kousa, the Kousa dogwood
This Asian dogwood comes into bloom in early June. It is resistant to many pests and diseases, including the anthracnose virus that has impacted our native white and pink dogwood trees. The bark of its trunk features exfoliated patches that provide year-round interest. Heart-shaped, dark green leaves are tough enough to withstand the summer heat.

There are many varieties of Kousa dogwoods, and you can examine them first-hand at Dogwood Days in Milton, June 5-20. The Mary May Binney Wakefield Arboretum is celebrating the bloom of 300 trees planted (and many propagated) by Mrs. Wakefield around the property. See www.wakefieldtrust.org for details of special events including themed tours, wellness programs, family activities, and music in the garden.
Image of Kousa dogwood full view in flower
Kousa dogwood full view in flower
Image of Kousa dogwood closeup
Up-close shot of Kousa dogwood
Your Essential Summer Watering Tips
When the Mercury rises, please don’t forget about your plants. This is especially true for any woody plant that was installed in the past three years and any perennial, annual, or vegetable planted this spring. Linked is my handy reference chart linking air temperature to watering frequency. In short, the higher the temperature, the more frequently we water.

And remember: if we get one inch or more of rain per week, you can relax this schedule for a day or two. Please be sure your irrigation system has a rain sensor so it will shut off appropriately, too.

Bulb Care in Late Spring
The heat and dry period put a fast end to the bulb show in late May. Now what?

Let your bulb foliage “ripen” or dry out in the summer heat, then remove it when it turns brown. This is how the bulbs photosynthesize and build up energy for next spring’s bloom. We have been scratching in bulb fertilizer around the declining foliage as an aid to future growth. Tulips, hyacinths, and daffodils can be deadheaded now. Avoid irrigating the spots where bulbs grow, as they prefer to bake in the dry heat of summer. You may want to interplant perennials that prefer these conditions as companions to help hide the declining foliage of your bulbs. Daylily and daffodils are just one combination that works well.

If you’re interested in adding more bulbs, please contact Priscilla and Laura now <phw@seedlingspecialist.com> This is the perfect time to plan additions for our upcoming late summer bulb order. We can also divide or transplant overcrowded stands of bulbs now, while we know where to find them!
Special Virtual Garden Tour in Concord - Friday through Sunday, June 25-27
The Concord Museum has planned its annual garden tour fundraiser as a virtual event again this year. Pumpkin Brook Organic Gardening is proud to be one of the Sponsors and to have another client property featured on the tour! Please see their website, www.concordmuseum.org for details of how to purchase your ticket and receive a link to the tour.
Priscilla’s Garden To-Do List for June

  • Keep up with weeding, lifting foliage of perennials to scrape small weeds
  • Plant final perennials, annuals, vegetables, shrubs, and trees by the end of the month
  • Follow summer watering instructions (attached)
  • Deadhead bulbs and early spring perennials as they fade
  • Fertilize bulbs to ensure good repeat bloom next year
  • Plan next fall’s bulb order
  • List plants to divide or add in fall in your garden beds
  • Change spring containers to a summer look and remember to water the new arrangements
  • Mulch bare soil areas to retain moisture and suppress weeds
  • Touch-up rose and hydrangea pruning done previously if there are any canes that didn’t leaf out well or developing new canes that are crossing in the interior of the roses
  • Leaf tier activity on hydrangea tips (with a pair of leaves stitched together by this insect pest) can simply be cut off and discarded
  • Finish planting vegetable gardens and mulch with sterilized straw or salt marsh hay to retain moisture and suppress weeds
  • Remember to harvest herbs and vegetables as they mature
  • Pinch tall asters, Joe Pye weed and rudbeckias to control sprawl later
I hope you can find the time to enjoy one of the featured garden tours this month and support some of our local nonprofit institutions. I’m planning to be there and hope to see you!

Priscilla and the PBOG Crew
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Pumpkin Brook Organic Gardening, Inc. 
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