Plant Health

Helping Plants During the September-October Drought

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By Pamm Cooper, UConn Home & Garden Education Center

A sloped yard showing signs of drought stress.
Drought stress on a sloped lawn. Photo by Pamm Cooper

Here at the UConn Home and Garden Center we have been getting questions about lawn and garden issues that have been particularly widespread in the state. Whether in the landscape or the garden, there is always something going on, good or bad, and keeping up with pests or cultural issues can be challenging. Because of the extended late season drought conditions this year, plants may be showing signs of stress. There are some basic things homeowners can do to help plants go into winter as healthy as possible.

Plants in temperate climates, like we have in New England, are normally manufacturing food to enable carbohydrate storage for new growth that will occur next spring. To do this, plants need both sunlight and water, and our extended drought conditions have limited most plants to enter survival mode, and carb storage is a second priority. The best way to help your plants is to water deeply any that still have green leaves. People with wells may need to determine if this is a priority for them. We can hope for a warm winter or insulating snow cover to help any plants with shallow roots survive until warm weather returns.

Drought stress on dogwood leaves
Drought stress on dogwood leaves. Photo by John Ruter

One sign of drought stress in woody broadleaf plants is leaf edges that curl upward. This is a good clue as to the beginning of water stress. Make sure to water these plants deeply, to ensure roots will be able to pick up the water. Usually the next day, leaves will start to uncurl if adequate water is applied. If drought stress continues, leaves may turn brown at the edges and early leaf drop may occur.

Evergreens, even established ones, can benefit from regular watering as long as the soil is not frozen and drought conditions remain. Evergreen foliage, whether needles or leaves, photosynthesize all year, and it is important that soil is not dry. Normally, we have snow that melts on and off, and if soils are not frozen, roots will be able to take up water and photosynthesis can still take place.

Perennials of certain species may be doing fine in this drought. Yarrows, some ox-eyed daisy cultivars, obedient plants, goldenrods, mountain mints and Agastache may be showing no signs of stress. Still, if any have green leaves at this point, consider watering them if dry and warm conditions continue.

This weekend I planted a small shrub, and I had to dig about fourteen inches down to accommodate the root mass. I have to say that I was surprised that the soil, not particularly one that dries out often, was powdery to the bottom of the hole. If you are planting anything now, make sure to water the soil thoroughly as you fill in the area around the roots, then water again when done. This is especially needed for small trees and shrubs but do the same for perennials.

Next year, woody plants that were impacted by drought this year may be more susceptible to certain diseases like verticillium wilt, Nectria canker and evergreens to Rhizosphaera needlecast. Be vigilant and scout for any signs or symptoms of these diseases.

Lawns that did not receive any rainfall or supplemental watering during the past two months may be dormant and crunchy at this time. It may not be clear if the grass will recover when temperatures cool and adequate water is applied. Some grass species may be dead, but it may not be clear until next spring when they fail to green up. There still may be time to apply supplemental irrigation, and with warm temperatures, grass may or may not green up, but at least the crowns may be kept alive to generate new leaves next spring. If any lawn areas were seeded in late summer, water new grass as needed. If it is wilting, water it for sure.

Be alert to what is happening in your own backyard, for the sooner you discover any problems the better. Contact us at the University of Connecticut Home and Garden Education Center for advice on lawns, landscapes, and other gardening subjects. Here's hoping for some needed rainfall and cooler temperatures to help our plants recover from the trying drought of 2024.

Penn State Extension has a good article on long-term effects of drought stress- https://extension.psu.edu/the-long-term-impact-of-drought-on-trees-and-shrubs

If you have questions about caring for plants during a drought, or if you have other gardening questions, feel free to contact us, toll-free, at the UConn Home & Garden Education Center at (877) 486-6271, visit our website at www.homegarden.cahnr.uconn.edu or contact your local Cooperative Extension center.

Is Early Leaf Drop an Indicator of Tree Health?

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By Nick Goltz, DPM, UConn Home & Garden Education Center, Plant Diagnostic Lab

Trees showing their autumn colors
Trees showing their fall colors. Photo by Nick Goltz

The autumnal equinox, one of two times of the year at which day and night are equal in length, just passed on Sunday the 22nd. While this point marks the astrological start of fall, many of the trees lining the roads on my drive to work (and in many of our clients’ yards) seem to want to get a head start on the season. Since late August, we’ve been getting calls from folks across Connecticut asking why the leaves on their trees are changing color and falling early. You may even be thinking, “Hey, a few of my trees are dropping their leaves early too. Is that something that can indicate how healthy they are?” In a word, maybe!

First, let me share the good news that, for most trees, premature color change and leaf drop doesn’t mean that they are in any immediate danger. Plants, much like humans and other animals, respond to stress differently depending on their environment and the kind of year they’ve been having. Just like we might see a little hair loss after a particularly stressful few months, trees may drop their leaves early as a response to stress. Identifying what is causing the stress however, is important when deciding if concern is warranted.

What type of stressors might be causing this early color change and leaf drop? For most trees, the answer is water. Connecticut and several other states in New England had a series of heavy rain events and flash flooding throughout the summer. While we’ve had hardly any rain in the land of steady habits for several weeks now, for many trees, the damage has already been done and symptoms are just appearing now. Saturated soils deprived plant roots of oxygen, damaging them and making them more susceptible to disease. Plants in especially low-lying areas, caught in floodwaters, or grown in poorly-draining clay soils likely experienced the most damage and earliest leaf drop.  Some plants may have even perished outright from the damage. Besides water, excessive heat and the increased prevalence of fungal and bacterial diseases, as well as some insect pests, may have also contributed to the stress our plants are letting us know about now.

So, how can you know if the early color change or leaf drop is an issue for your favorite tree or just its way of complaining about a stressful summer? When and where the leaf change and drop is occurring can help you determine if the damage is likely a normal stress response or due to something more sinister.

Consider when the color change and leaf drop first began. In this instance, seeing some leaves begin to change in the last week of August is less concerning than seeing them change at the end of June. Plants that have their leaves change color and drop in midsummer or earlier are most likely dealing with a disease or pest issue, rather than a stress response. I recommend you get advice for these plants by contacting the UConn Home & Garden Education Center and remove them from your garden if they are unlikely to recover.

Also, consider what part(s) of the canopy was affected. Conifers such as white pine drop their leaves (we usually call them needles) in response to stress too, but you will typically see this take place on the interior of the plant – the older needles that aren’t capturing much sun anymore. Branches on deciduous trees, such as oak, that are in shady spots tend to drop their leaves early too, and this is normal.

Branches in full sun that lose their leaves very early, while others on the tree remain fine, are a bit suspicious. Mark these branches with tape or string and monitor them carefully as the plant produces its first leaves or flowers in the spring. If these marked branches do not produce leaves or flowers with the rest of the tree, get advice (again, by contacting the folks at the UConn HGEC)! The best option is usually to cut them close to the main trunk, then disinfect your pruning tools.

If you’re concerned about the health of your tree, including as a result of a potential disease or pest issue, practice good fall habits to give your trees the best foot forward next spring! Clean as much leaf litter as possible and remove it from the base of trees that dropped their leaves early. If you suspect the plant is diseased or has pests, throw away these leaves or burn them before composting. For example, many plant pathogenic fungi can survive the winter on fallen leaves and reinfect healthy plant tissue the following spring. It’s also a good idea to minimize added stress for your plants. Try not to expose them to herbicides, deicing salts, fertilizers, or other chemicals until they’re looking strong again.

If you aren’t sure how to proceed with your fall cleanup or if you’d simply like a second opinion on your favorite tree, get free horticultural consultation from the UConn Home & Garden Education Center by emailing ladybug@uconn.edu or by calling (877) 486-6271.

End of Season Strawberry Renovation

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By Dawn Pettinelli, UConn Home & Garden Education Center

Strawberry row
Strawberries before renovation at the end of the season. Photos by dmp2024

Strawberry row after renovation
Strawberries after renovation at the end of the season. Photos by dmp2024

So, you decided to grow some strawberries this year. You carefully prepared the bed and have enjoyed your first crop. Now you are wondering what to do to keep your strawberry bed healthy and productive. In part, the care after harvest depends on whether you are growing June bearing or day neutral (everbearing) varieties and what kind of row systems you have them planted in.

June bearing strawberries are most commonly grown in what is known as the matted row system. Mother plants are set 18 to 24 inches apart in 3 to 4 1/2 foot rows and runners are allowed to root anywhere within the row. This system is usually the easiest to maintain. Typically, at the end of the third growing season both plant quality and fruit quantity start to decrease and the whole bed is dug up and replanted with new disease-free strawberry plants. Try to incorporate this into your garden rotation plan to reduce disease problems.

June bearers can also be grown in single rows composed of different aged plants with the original plants set about a foot apart. A second row is started with first year runners and set 18 inches from the initial planting. Use only the first or second daughter plants produced along the runners because they are the most vigorous and productive. The rest are usually discarded.

The next year a third row is made again using the first one or two daughter plants and once more surplus runners and plants are removed. After the original mother plants have produced fruit for about 3 years, they are generally replaced with new, disease-free stock and the cycle continues. This way one always has a row or two of strawberries in production. Ideally the row with the new strawberry plants should be located on a section of the garden where strawberries haven’t been grown for 3 to 5 years. This isn’t always possible in small yards, which is why it is important to purchase certified virus free stock.

After year two when June bearing strawberries have finished producing their crop, it is time to renovate. According to Evan Lentz, UConn Fruit Specialist and Assistant Extension Educator, renovating your June-bearing strawberries is one of the best ways to maximize your annual production, reduce disease instance, and maintain an orderly planting. Proper renovation ensures that you set yourself up for success in the following year and allows you to extend the life and productivity of this semi-perennial crop. This is doubly important for individuals producing fruit in an organic or no-spray system.

This can be done sometime in July through August. Lentz suggests starting by either mowing or clipping with hand trimmers all the foliage about 2 inches or so above the crowns. Next, go through the bed removing all weeds, and weak and extra strawberry plants and dead or dying leaves. Thin to space plants at least 10 to 12 inches apart and cultivate around these remaining plants.

Now is the time to fertilize your strawberries whether beds are renovated or not. Lentz recommends working in about 3 to 4 pounds of 10-10-10 or its organic equivalent per 100 square feet. Lightly scratch the fertilizer into the soil. Brush or rinse any fertilizer off leaves at the salts will injure them.

Day neutrals, such as ‘Tristar’, ‘Seascape’ and ‘Mara des Bois’ produce a fairly decent size crop in June and continue forming occasional berries until frost. Unlike June bearers which develop fruit buds in late summer and early fall, the ever bearers have the ability to form fruit buds throughout the summer. An advantage to growing day neutrals is you will still get strawberries even if a late spring frost kills their initial fruit buds.

In general, day neutrals are grown for 2 or 3 years and then a new batch of strawberries is planted. The day neutrals produce far fewer runners than the June bearers. The new daughter plants should all be removed although they can be transplanted into another area if desired. Plants are usually set one foot apart in single rows about 18 inches wide.

According to Lentz, all strawberries require at least an inch of water per week for vigorous growth. If dry weather sets in, plan on irrigating plants, especially those just renovated. Use a mulch of pine needles, straw or wood shavings to conserve moisture, keep weeds down and berries off the soil. Since strawberries are shallow rooted, it is important to keep weeds under control.

It does take a little time to maintain a strawberry bed but the luxury of picking your own berries for strawberry shortcake, jam or fresh eating makes it all worthwhile. If you have questions about growing strawberries or on any other home or garden topic, contact the UCONN Home & Garden Education Center, toll-free, at (877) 486-6271, visit their web site at www.homegarden.cahnr.uconn.edu or contact your local Cooperative Extension Center.

Flock to Phlox

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By Dawn Pettinelli, UConn Home & Garden Education Center

Purple phlox flowers
Purple phlox in bloom. Photo by dmp2024

About now, many of our perennial gardens are looking a bit lackluster. Early summer bloomers have fizzled out and autumn charmers like asters and mums have yet to pop. Garden phlox (P. paniculata) to the rescue!

Annual and perennial phlox comprised about 70 different species, many of which are native to North America. Their habitats range from woodlands to meadow and their growth habits from low and mounded to tall and upright. All have clusters of tubular flowers that are exceptionally attractive to hummingbirds and hummingbird moths along with bees and butterflies.

There are an outstanding number of garden worthy cultivars. My favorite is ‘David’, a white, powdery mildew resistant variety that grows to about 4 feet with loads of slightly fragrant blooms. I have it planted in my white garden and this sturdy, upright plant has come back year after year with virtually no problems.

UConn Plant Science & Landscape Architecture professor, Dr. Jessica Lubell-Brand noted phlox ‘Jeana’, the 2024 Perennial Plant Association’s Perennial Plant of the Year, is treasured for its long blooming period as well as its butterfly luring abilities. Plants can reach up to 5 feet in height and its more loose and wild appearance works well in cottage gardens featuring attractive pink flowers and decent powdery mildew resistance.

Sometimes shorter varieties are a better fit and if that is the case, for your beds look to ‘Coral Crème Drop’, which according to Dr. Lubell are part of the Candy Store series. She raves about their vibrant coral blossoms with their August feel. Another top garden candidate in her book is ‘Glamour Girl’, also with hot coral blooms as well as good resistance to powdery mildew.

A number of garden phlox sport distinctive eyes. ‘Bright Eyes’, as the name implies is a delicate pale pink with a bright crimson eye while ‘Laura’ is a mildew resistant, royal purple variety with a white eye. Both grow to about 3 feet in height.

Many gardeners find these phlox indispensable for August into September color in the perennial garden. They are tough, colorful, vigorous plants that are hardy and relatively long-lived. They make excellent background plants for narrow borders and can bridge the gap between varied sized perennial plantings. Garden phlox come in a wide range of hot and cool colors ranging from white and light pinks, to purples, reds, oranges and magenta.

For healthy, vigorous plants, they should be grown in full sun to part shade. Phlox enjoy a moderately fertile soil with a pH in the 6s. While established plants are fairly drought tolerant, larger and more numerous flower heads are produced when adequate moisture is supplied. They grow at a moderate rate so division every 3 to 4 years is usually sufficient.

Both to encourage sizable blooms as well as to reduce the incidence of phlox’s number one nemesis, powdery mildew, Dr. Lubell recommends reducing the number of stalks early in the growing season to 6 to 8 per plant. This provides better air circulation to plants.

Powdery mildew on phlox leaves
Powdery mildew on phlox leaves. Photo by dmp2024

Powdery mildew is a fungus disease that is more widespread during humid, wet summers. It typically does not kill plants, but they look awful with their leaves covered with what looks like white powder. Two options for dealing with this disease according to Dr. Lubell, are to select resistant phlox cultivars or to pre-emptively spray with a least toxic substance like potassium bicarbonate or your fungicide of choice. As stems die or get killed by frost, be sure to remove them from the garden and put in the trash, not the compost pile.

Insects are not usually a problem but during dry, hot summers, spider mites may attack plants. Usually, a strong blast from the hose will knock them off. This may need to be repeated several times if dry weather persists.

A key gardening practice when growing phlox is dead-heading, or removal of spent flower heads. Garden phlox produce a lot of seeds and if left to fall to the ground and germinate, vigorous plants will most likely produce blooms in that undesirable, muted magenta color. Often these seedlings crowd out the more desirable cultivars that were intentionally purchased.

Not only are garden phlox cultivars pretty spectacular on their own but Dr. Lubell says they pair nicely with a variety of other perennials including lilies, yarrow, ballon flower, daylilies, bee balm as well as numerous annuals.

If you have questions on garden phlox or on any other gardening questions, feel free to contact us, toll-free, at the UConn Home & Garden Education Center at (877) 486-6271, visit our website at www.homegarden.cahnr.uconn.edu

Calling the Cut – Tree Triage, Care, and Removal

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By Nick Goltz, DPM, UConn Plant Diagnostic Lab/UConn Home & Garden Education Center

The forecast is looking good for a perfect 4th of July weekend. Most folks will take advantage of the weather ahead to plan that perfect grilling menu for when their friends and family visit. This is a much-needed respite from the severe weather that passed through over the past few weeks. Severe winds and torrential rains hammered Connecticut and most of the rest of the Northeast after a recent heat wave. With the weather for the week ahead of us is looking much better than the weather of the week behind us, now is the perfect time to assess our trees and determine if any action needs to be taken before the next storm comes!

Tree with branches missing on one side.
Storm damage caused this tree to lose branches on one side. This lopsidedness increases risk to property below. Photo by H. Zidack

I’ll start and end this column with the advice that a professional arborist should be called-in if you are ever unsure of your tree’s health, or if you need support regarding safe management and potential removal. In Connecticut, one of the best resources for finding a licensed, local arborist as well as additional resources regarding tree care and maintenance can be found on the Connecticut Tree Protective Association website, ctpa.org. That said, tree triage can start with you at home. There are many things one can be on the lookout for to determine if a tree need professional attention, and potentially in what order the work should be done.

I’m sure you’ve heard this phrase used to describe real estate, but with trees too, location is everything. The first thing to consider when performing your tree triage is the location of the tree. Regardless of tree age, size, species, or health, the trees that should always merit our immediate attention are those in locations where they could pose a danger to life or property if a limb were to fall off or if the tree were to topple altogether. Trees within striking distance of homes, power lines, and important structures like chicken coops and pet houses should always be the first inspected before the storm comes and after it passes. If a tree knocks down a power line or hits a home, call for help. Never attempt to work around a live cable (one that still carries electricity) without the proper training and equipment.

The second thing to consider as you perform your tree triage is health of the tree. Trees weakened by disease or age are more likely to succumb to strong winds or topple after standing water weakens or kills roots. Inspect your trees for symptoms of stress and disease such as branches that no longer produce leaves. Depending on the species of tree, a few may not be much cause for concern, but if there are several branches on a tree that no longer produce new leaves or needles, the tree is likely not in great health. Another symptom of stress or disease is a visible canker, or large wound, on the trunk of the tree. Trees in good health will typically grow new tissue over an injury sustained by pruning, animal feeding, or a previous storm. Cankers that appear to be getting larger over a few years, rather than smaller, are often a cause for concern.

There are even some obvious signs of disease such as conk or shelf mushrooms that grow directly from the wood of the tree. While these organisms are important for nutrient cycling in natural ecosystems, they often indicate that a tree is approaching the end of its life. The shelf mushroom is only the sexual structure of the fungus, there to produce spores and reach new trees. While removing the mushroom may slow the spread of the fungus to other trees nearby, the majority of the “body” of the fungus will still exist within the tree, weakening it by breaking down woody tissue over time.

Trees, like other living things, do not live indefinitely and become more vulnerable to illness and stress as they age. Just like people need to take care of themselves to ensure they live a long, healthy life, so too must trees be cared for over the course of their lives to ensure they have the best possible outcome. Regular fertilization and pruning are essential to not only ensure that a tree grows robustly, but also that it does not become lopsided or heavy on one side as it ages. Even healthy trees can fall if they are never pruned and have a poor center of gravity! Pruning should be performed frequently to promote new growth, discourage lopsidedness, and allow increased airflow through the canopy. This will have the double benefit of decreasing disease pressure that often accompanies high canopy humidity and prolonged leaf wetness. Though it depends on the species of tree, most here in New England perform best when pruned while they are dormant in winter. Remember to not remove more than 1/3 of the tree’s branches when pruning, if possible!

There are other factors to consider when determining if a tree should come down that we don’t have space to discuss at length here, such as the species of tree, whether the tree is used for other purposes (such as part of a living fence), whether the tree has historic or personal significance, or what removal of the tree may mean for other plants nearby that depend on its shade. And, of course, nobody should consider tree removal without considering cost and time. If cost is a concern, remember to do your triage and prioritize the management of trees that could potentially damage your home, property, or power lines if they were to fall. These considerations and others are worth discussing with an arborist as they survey your property!

For questions about planting and pruning trees or other gardening topics, feel free to contact us, toll-free, at the UConn Home & Garden Education Center at (877) 486-6271, visit our website at www.homegarden.cahnr.uconn.edu or contact your local Cooperative Extension Center.