July 2021

Two common buckeyes among blue vervain and boneset flowers

“Along the river’s summer walk,
The withered tufts of asters nod;
And trembles on its arid stalk
the hoar plum of the golden-rod.”
–  John Greenleaf Whittier

July marks the midway point of the year, when the natural world really gets going and the excitement never ends. It is the time of gathering dewberries and the flights of swallowtail butterflies. Insects get more interesting, plants are flowering with a vengeance and rainbows and sun halos bring added interest to the skies. There is still enough warm weather yet to come, and everything just seems more enjoyable when happened upon in the garden or in the wild.

Orange glow from wildfire haze in the western United States just after sunrise on a foggy morning in late July 2021

This year so far has been for the birds. There are Carolina wrens nesting in my propane tank cover, a wood duck and her young at a pond where I work that is in a very busy area, and the gardener at work discovered a hummingbird nest, which can be hard to spot as the outside is covered with lichens and often blends in with the branch it is on.

Wood duck mother and her little flock head for cover provided by cattails.
Young hummingbird is almost ready to leave the nest

Native Nymphaea odorata water lilies are fragrant and white. Walking around a friend’s property where there is a large pond, the surface of the water was covered with the first pink water lilies I ever saw in a natural setting. They may have been put in years before when ornamental N. odorata varieties that were hardy became available.

Swallowtail butterflies are suddenly in profusion and their caterpillars are always a good find. Knowing the host plants is the key. Check out small cherries and tulip trees for tiger swallowtail cats that sit right on top of a leaf.

Caterpillar of the eastern tiger swallowtail

Crawling across the lawn one evening was a pretty large beetle with mandibles to be feared by lesser creatures. It was a male yellow-thighed stag beetle Lucanus capreolus. Males use their oversized mandibles to fight with rivals in order to mate with a nearby female.  These beetles make a loud buzzing sound in flight and are attracted to lights.

Lucanus capreolus. stag beetle

Hiking in Ayers Gap woods there was a string of silk across the trail. Hanging on it was a Micrathena gracilis spined orb weaver spider. Also known as the castleback orb weaver because of the unusually large abdomen with spines sticking out like turrets, females rebuild only the center of their web daily, not the whole web like most other orb weavers.

Female spined orb weaver
Top view of Micrathean gracilis
Indian pipe in woods at Ayers Gap

Some wildflowers that bloom now in wetland areas are monkey flower, boneset and Joe-pye weed. These attract many species of butterflies and pollinators and are often found together along stream and pond edges and swamp borders. The fragrant flowers of Clethra alnifolia, a wetland shrub, make this a plant that can be smelled long before you see it.

Monkey flower Mimulus ringens
Clethra alnifolia

Here’s to enjoying the rest of summer, keeping cool, and finding nice little surprises as move too quickly toward the colder fall and winter landscape of New England. Like this piglet from Organic Roots farm, find a way to stay cool on those hot days.

Pamm Cooper

The UConn Plant Diagnostic Lab (https://plant.lab.uconn.edu/) receives many samples of rhododendrons as well as emails from clients wondering why their plants have dead stems and dieback. Rhododendrons are very common landscape plants loved by many homeowners, but they can have a few disease issues. One common disease that we see frequently is Botryosphaeria dieback.

Botryosphaeria dieback is caused by the fungal pathogen, Botryosphaeria dothidea. Symptoms include wilting leaves that roll inwards along the midvein with dead leaves remaining attached to stems. Leaves begin to turn dark green to brown and eventually die because stem cankers block and girdle the stem. Reddish-brown and sunken cankers are found on stems and branch tips. Stem discoloration can extend to the wood and pith, and a cross section of the stem often shows a darkened wedge pointed towards the center of the stem. The infection can extend down branches into the main stem, killing the plant. On older plants, cankers and dead wood can develop black pycnidia, which are fruiting structures of the fungus.

Botrysphaeria dieback on rhododendron. Photo by Elizabeth Bush, Virginia Polytechnic Institute & State University, Bugwood.org

Infections can occur through natural wounds, pruning wounds, leaf scars, or dead branches. Exposure to conditions such as heat or drought stress can make plants more susceptible to infection. Plants exposed to full sun are frequently infected.

Botryosphaeria can also be confused with symptoms of phytophthora infection. Botryosphaeria cankers usually develop more slowly than phytophthora cankers. Phytophthora cankers can extend to the leaves and form brown wedges of discoloration at the bases of leaves and down the midvein. Winter injury symptoms can also look like Botryosphaeria, including tip dieback and leaves rolled along the midvein. Young transplants that have not been acclimated to winter conditions or entered dormancy are often affected by winter injury. Winter injury can be avoided by planting cold tolerant cultivars and following good cultural practices.

Note the reddish color of stem tips and leaves along the midvein. Photo by David L. Clement, University of Maryland, Bugwood.org

Planting site characteristics such as light exposure and soil drainage are important things that diagnosticians consider when a plant is showing symptoms of disease. It is important to know how often your rhododendron plants are getting watered and if the soil has good or poor drainage. Proper irrigation and fertilization can help prevent plants from becoming susceptible to infection. Rhododendrons should be planted in partial sun and watered during periods of drought. Fertilizer applications in late summer or early fall can cause plants to push out new growth that does not harden off properly for winter conditions. These stems will likely suffer from cold injury and become entry sites for infection in the spring.

Managing Botryosphaeria dieback includes the preventative controls listed above. Additionally, all diseased or dead tissue should be pruned away during dry weather. Make pruning cuts at least 6 inches below where symptomatic tissue ends and sanitize tools between cuts with 10% bleach solution or 70% alcohol. Remove all diseased tissue to prevent the disease from overwintering or spreading to healthy plants. Either place in trash or burn it. Following good cultural practices is always recommended when managing disease. Avoid overhead or sprinkler irrigation, as this causes prolonged leaf wetness and aids in disease spread. Avoid wounding plants and encourage good air circulation by clearing the area around plants of any debris or weeds. Sanitation and cleanliness of the planting site is important and often overlooked. Remove any leaves or branches that have fallen to the ground throughout the growing season and do one last sweep in the fall. Fungicide applications are not effective or recommended for use against this disease, so preventative and cultural controls are most important for management.

Lillian Borbas

“Rain, rain, go away, come again some other day.” We used to sing that song as kids. After starting the spring and summer with some of the driest weather we have had for some time, we are now inundated with rain. The only advantage to this is that seed starting was easier, but only because the soil was heated up a lot by the time this rain hit. Otherwise, all the seed would have rotted. Unfortunately, we seem to be getting more rain than we bargained for…

7-15 Rudbeckia falling over ML

This perennial Rudbeckia patch is flopping over due to recent heavy rains. Photo by mrl2021.

A good soil will hold moisture and therefore help the plants survive between rain spells. In our garden, we water long before the plants would suffer. When it rains as much as it has, the soil can become waterlogged, leaving no space for air. This is a horrible condition for our plants to grow in. Unfortunately, there is not much we can do about it now. Raised beds help excess water drain away from our plants, but those would have had to be installed before planting in the spring. There really is no way to cover the plants to prevent the rain from hitting them as the water table is so high it would not matter (not to mention the plastic and humidity would make matters worse).

Mold, mildew, and fungus thrive in this kind of environment. Don’t be surprised if your cucumbers, squash, and phlox become covered in it this year. There are sprays that help, but I generally do not do anything and hope for more sunlight. Soil borne diseases that affect the roots will be greater in number this year as well. Hopefully we dry out soon before this becomes a bigger problem. Pollinators are limited when the rain comes, and because of this we should expect lower pollination rates for our vegetables for the time being. 

Your plants may appear to have the lower leaves yellowing. This is normal when they are given too much water. Once again there is no way to stop the rain so just hang in there. Yellowing can also be a symptom of nutritional deficiency (particularly nitrogen). Rain continually washing through the soil many times can wash away nutrients. This is called leaching. You would be wise to put some fertilizer down to replace what was lost, but try and not put it down before a big rain storm. Organic fertilizers tend to work better in this case as they are less prone to leaching. 

7-15 Yellowing Zuchinni plant ML

Yellowing of lower leaves of this zucchini plant caused by too much water. Photo by mrl2021.

Another thing to watch out for that you can do something about, are the weeds! The moisture and warm soil will help them germinate as well. Weeds may outgrow our plants in certain conditions. Get out there while the weeds are still small with a stirrup hoe or any hoe you prefer and get them before they get too big. When they are small, the hoe can cut or disturb weeds in a way that kills them. In many cases, if left unchecked, the weeds will grow taller than our plants and shade them out. A few weeks from now our prized plants may be totally outcompeted! Manually remove any weeds too big to hoe up. The wet ground usually makes weeds easier to pull so at least there is some good that comes from all this precipitation.

7-15 Weedy peppers ML

The pepper patch is in need of the hoe. Photo by mrl2021.

7-15 Raspberry and tall grass ML

This spring-planted raspberry patch is being overtaken by grass – time to weed before it gets shaded out completely. Photo by mrl2021.

Over saturated ground may also cause trees to uproot – especially pine trees. Be very careful if you see trees that seem to be leaning over. Hard, frequent rain can also cause washing out of the yard where the grass may not have been that thick.

7-15 Washing out in thin grass ML

This area of the yard was due for reseeding but now has washed out. Photo by mrl2021.

Tall annual and perennial plants may also get pushed over by the heavy rains. You may be able to tie them up with some string, as they probably will not stand up on their own again this year. If perennial, they will come back next year and have a normal, upright growth pattern so no worries there.

7-15 Cosmos spilling into the lawn ML

The Cosmos are spilling over into the lawn. They will need to be tied up before mowing. Photo by mrl2021.

7-15 Crocosmia flopping over ML

The Crocosmia is flopping over this year. I could tie this up after the rains end. Photo by mrl2021.

Hopefully this blog helped you understand what is going on around you. With the exception of weeding, there is not much we can do about it other than pray it stops raining so much! This will all end sooner or later and will be a distant memory. I guess we should be happy we did not have to lug around the garden hose. Be ready to fertilize when the rain ends and tie up some of your prized plants. This is all part of what we have to deal with when gardening. In many respects, although outside of the norm, it is nothing new. Maybe one day soon the lawn will be dry enough to mow!

Matt Lisy

Now that most folks’ soils have been tested and gardens planted, there’s been time to peruse and spiffy up the perennial and shrub beds, and invariably plant questions arise. A not uncommon query is regarding variegated plants that send up all green shoots.

goutweed var w grn

Variegated goutweed with green stem. Photo by dmp, UConn

It seems gardeners either really love variegated plants or really do not care for them. Personally, I find many variegated plants quite attractive especially when trying to dress up a dull corner or bring a glimmer of light to a shaded area. The uniquely patterned foliage worn by some of our most popular variegated plants is one of Mother Nature’s marvels. So, why oh, why are stems of variegated plants turning green?

An understanding of how variegation in plants occurs might help. Natural genetic mutations are occurring all the time in people, animals, and plants. Plant enthusiasts take note of those happening in plants. Maybe a shoot or branch or flower is produced that is different from the rest of the plant. The color, size, growth habit or bloom type may vary. This is often referred to as a sport. Occasionally, intriguing growth characteristics are caused by insects or diseases. Only sports caused by genetic mutations can be propagated.

Heliopsis Loraine Sunshine w sport

Heliopsis Loraine Sunshine with green shoot. Photo by dmp,2021.

Not only are variegated plants the result of genetic mutations but many of our dwarf conifers and weeping versions of trees and shrubs are as well. Witches brooms, which are congested collections of multiple shoots on one part of the plant, are good natural mutations that have given rise to many types of dwarf conifers. Once that most people are familiar with is the dwarf Alberta spruce (Picea glauca ‘Conica”).

If deemed interesting enough (i.e. a marketable commodity), it will be propagated by divisions, cuttings, or tissue culture. Vegetative propagation, as opposed to seed cultivation, is required to maintain the unique coloring or growth characteristics. If seeds are sown, more interesting variations may or may not occur. 

Gardeners delighted by these unique variegated, dwarf and weeping plant forms are often dismayed to notice solid green leaves or full-size branches or even upright growths on their prized specimens. This is known as a reversion and is a natural process by which the cultivar reverts back to the original form found in its parentage.

spirea with solid green branch

Golden spirea with a green leaved branch. Photo by dmp, 2021.

Reasons that reversion might occur vary. Perhaps there are unstable changes in cell mutations. Maybe the environmental conditions that the plants are exposed to are not a good fit for the plant in terms of light availability. Cold or other injuries may stimulate latent buds. No one cause for all reversions likely exists.

When variegated plants start sending out all green shoots, the explanation may be the most straightforward. Some common variegated perennials include brunnera, phlox, sedums, obedient plants and heliopsis. The leaves of these plants may be edged, striped or frosted with cream or white areas. Where there is no green on the leaf, there is no chlorophyll and it is this pigment that is able to absorb energy from the sun that the plant can use for photosynthesis. More variegation, less chlorophyll, often resulting in weaker, less vigorous plants with smaller leaves.

sedum var w grn shoots

Variegated sedum with green shoots. Photo by dmp2021.

Of course, we gardeners have a tendency to tuck these illuminative plants in shadier areas to brighten then up. This means even less light reaching the leaves so plants may send out solid green leaves to give themselves a better chance of capturing more sunlight ensuring their survival. Even variegated plants in sunny sites may produce solid green shoots, however, so just lack of adequate amounts of sunlight does not account for all reversions.

Stranger looking are the growth reversions in trees and shrubs, especially dwarf evergreens, like the Alberta spruce. It is quite a sight to see what looks like a regular size spruce branch arising from the dwarf Alberta spruce.

Alberta sprunce w sport2

Alberta spruce with sport. Photo by dmp, UConn

Since the solid green growth or full-sized leaves or needles on herbaceous and woody plants can photosynthesize more efficiently, they will prevail unless we remove them. If not pruned out in a timely fashion, they will often overtake the weaker variegated or dwarf plant parts and once they do, their effects typically cannot be reversed.

Inspect your variegated plants on a regular basis and remove any solid green shoots when young. Keep an eye on dwarf evergreens and weeping forms as both are often grafted and may send out full sized parental shoots or upright shoots, respectively. Remove these to keep your plants attractive and growing in the desirable form.

sedum var remove grn

Removing the solid green shoots on the sedum. Photo by dmp2021.

Don’t let the possibility of reversions deter you from selecting variegated plants for your gardens. Many remain stable for a good long time and serve as attractive accents, complements or contrasts to existing plantings.   

Dawn P.