Hot, dry summers are not that unusual in the Midwest, but 2020’s hot dry spell started considerably earlier than usual, before summer even officially began! To make it a triple whammy, the hard freeze in early May caused some landscape plants to burn up more stored carbohydrate reserves to produce a second round of foliage. I’m sure I don’t have to point out that most of Indiana is currently experiencing abnormally hot, dry conditions. Although recent rains have brought relief to some areas, any respite is sure to be temporary. Seasonal thunderstorms may deluge some landscapes with water while other areas, even those close by, may stay fairly dry. Much of the area has experienced highs in the upper 80’s to over 90º F over the past month. Leaf scorch on trees and shrubs, appearing as a browning along the edges of the leaves, is very common in dry[Read More…]
2020 has jumped the shark!
A mild winter, followed by a brief warm-up, caused many plants to flower or leaf out before one last freeze. Unfortunately, that succulent new growth is much more susceptible to frost and freeze damage. Freeze injury in many plants will occur when the temperature falls below 32° F (0° C) and the water within the plant’s cells freezes. The ice crystals that develop in the cells puncture the cells, killing them when the tissue warms up, and the cell’s contents leak out. Symptoms of this type of damage include dark green and water-soaked leaves that later turn black as the tissues dies. The speed of this process has a great deal to do with how quickly the plant warms up. With our last two freezes, many people did not see significant damage until the second freeze event when even more susceptible tissue had emerged. Some plants are better adapted to[Read More…]
Assessing Freeze Injury on Horticultural Plants
As so many gardeners are staying at home these days, we’ve had more opportunity to enjoy the spring display. And then, perhaps inevitably, “normal” spring frost and freeze visited – some plants are vulnerable to damage. The amount of damage will depend on how far along they are in their development. Home fruit-growers may have reason to be concerned: At 28 F, you can expect a 10 percent loss of flowers/young developing fruit. However, at 25 F that loss increases to 90 percent! Much of Indiana dropped to the mid 20’s on the mornings of April 15 and 16. (Fig. 1) For home growers, covering plants with sheets or blankets might provide a few degrees of protection. (Fig. 2) Bud counts were good until the freeze, so in some cases, even just 10 percent retained fruit might still be a decent crop on our tree fruits. Grapes may also still[Read More…]
Mounds upon Mounds of Mulch
Usage of mulch at the base of trees is a very common and recommended practice to protect the trunk from mower damage, as well as improve root conditions by preventing weed and grass growth in the root zone. Mulch also increases moisture retention in the soil, and improves soil quality as it breaks down over time. However, there is such a thing as “too much of a good thing.” Over-application of mulch, in the form of piles or “volcanoes” mounded up the trunk of a tree, will prove detrimental to the health of the tree and can lead to premature death (Figure 1, 2, 3). This is an unfortunate and fairly common occurrence in the landscape. Plants are remarkably plastic organisms, meaning they have an incredible capacity to adapt to the environment and conditions around them (Figure 4). They have to because they cannot pick themselves up and find[Read More…]
A Look Back at a Challenging 2019 Season
The 2019 season provided challenges that were unexpected to the Green Industry, which included an abundance of rainfall followed by drought-like conditions, new invasive pests, concerns about glyphosate use, and many others. The Purdue Landscape Report focuses on timely articles that help Green Industry professionals make decisions for their business and keep abreast of looming issues. As we begin the 2020 season, we can take a look back at some of the top stories from 2019. Hopefully this season will be a little less challenging, but be sure we’ll be there with relevant, timely information in 2020. Thanks for following along! Boxwood Blight Found in Indiana https://www.purduelandscapereport.org/article/boxwood-blight-found-in-indiana/ Sudden Oak Death Found in Indiana https://www.purduelandscapereport.org/article/special-alert-sudden-oak-death/ Be on the Lookout for Defoliated Viburnums and Viburnum Leaf Beetle https://www.purduelandscapereport.org/article/be-on-the-lookout-for-defoliated-viburnums-and-viburnum-leaf-beetle/ Terrestrial invasive species rule signed by Indiana Governor https://www.purduelandscapereport.org/article/terrestrial-invasive-species-rule-signed-by-indiana-governor/ What nurseries need to know about the invasive species regulation[Read More…]
Urban Trees and Climate Change
The urban environment is tough for growing trees and our changing climate is going to make it even tougher. Planting trees is part of the solution, but not the answer. We can’t just keep planting trees; we have to start growing and sustaining existing trees.
Mother Nature Gives Spring Bulbs the Heave-Ho!
It’s not unusual for Indiana weather to have trouble deciding what season it is. Warm spells during the dormant period often lead to bulbs poking their foliage (and sometimes flower buds) through the soil. While we’re more used to seeing this happen during February warm spells, our frigid temperatures arrived a bit early in the Fall of 2019 followed by intermittent unseasonably mild weather. Indiana temperatures widely fluctuated in November and December, with the low temperature at the Purdue ACRE Farm (West Lafayette) of 25º F on November 7, 3º F on November 14, and 41º F on November 21! And the alternating pattern of below and above freezing continued through December. Correspondingly, soil temperatures also fluctuated from 63º on November 7, 36º on November 14, and 45º on November 27 at ACRE. There’s not much you can do about bulbs that have sprouted, but the good news is that[Read More…]
Winter injury update to Michigan trees and shrubs
The cold snap on Nov. 11, 2019, could have lasting impacts on trees and shrubs.
Deicing salts helpful for people but not landscape plants
Deicing salts can save your neck this winter, but they can spell disaster for landscape plants. Whether the salt is sprayed on the plants from passing traffic near the road or is shoveled onto plants near the sidewalk, the salt can cause damage. Salts can adversely affect plants in several ways. Salts deposited on the surface of twigs, branches and evergreen leaves can cause excessive drying of foliage and roots. They can be taken up by plants and accumulate to toxic levels. Sodium salts in particular can also cause a nutritional imbalance by changing the chemistry of the soil and harm soil structure. The most apparent damage is death of buds and twig tips as a result of salt spray. As the tips of the plants die, the plant responds by growing an excessive number of side branches. However, accumulation damage is more slowly manifested and may not be noticeable[Read More…]
The Silent Tree Killer- Compaction
Many tree issues are relatively easy to diagnose, but, when it comes to diagnosing issues below ground, where the roots are located, it becomes a bit tricky.
