Spring is a wonderful time of year. After months of dreariness and bare branches, bright, succulent green leaves and flowers of every kind and color have emerged. So too, have emerged gardeners and outdoor enthusiasts ready to tackle all their home and landscape improvement projects planned over the winter. However, this is also the time, when folks first start paying attention to their plants again, that strange, seemingly inexpiable plant problems crop up!
All plant problems can be divided into two categories: biotic problems, or issues caused by a living organism (think insects, fungus, and bacteria), and abiotic problems, issues that arise from things other than biotic pests. It’s the first category that people generally turn to when something goes wrong in their landscape or garden. It’s convenient to blame problems on pests and it’s very satisfying to go to the local home improvement store, buy a bottle of something and spray the problem into submission. But, in many of my consultations with clientele each spring, I find myself having to step back, consider holistically the circumstances causing the issue to arise, scout for pests and diseases, and if I find no evidence of either, encouraging the person to consider the possibility the problem is abiotic and to adopt patience and allow the problem to correct itself. Of course, this is never what anyone wants to hear. We always want a solvable problem with a simple cause and solution. But life isn’t always that easy and sometimes we must accept that we (nor a pest/disease) did anything wrong to cause the issue and, in some cases, that we ourselves actually caused the problem to happen in the first place! To illustrate, let’s consider two case studies from site visits I’ve had this spring.
Cold damage on Boxwood hedge
Three weeks ago, I got a call from a very concerned client. She had gotten her March issue of a popular outdoor magazine in the mail, in which was a feature on an emerging pathogen, Boxwood Blight, a nasty fungus decimating Boxwood populations in states north of us. She had also noticed the Boxwoods in front of her house had recently developed browning of their new spring shoots across most the hedgerow. Having read the article and matching the symptoms she’d noticed to the ones described in the magazine article, she was convinced her shrub was infected with blight and wanted to know if there was a cure. Agreeing that the symptoms sounded similar and wanting to rule out an infection of an extremely serious pathogen, I decided to go take a look. Upon inspection, it was obvious that Boxwood Blight wasn’t to blame. Damage from disease generally isn’t quite as uniform as what I saw. The new growth on top of the hedge was indeed brown but only where the eaves of the house and a nearby tree didn’t provide overhead cover and, to boot, the sides of the hedge were a very normal bright green. Having gone through a recent cold snap that brought several mornings of heavy frost and knowing that the weeks before that the weather had been unseasonably warm, causing many plants to begin growing prematurely, all signs pointed toward an abiotic problem, cold/frost damage that would clear up as soon as the plant put on another flush of growth. The client was delighted to hear she didn’t have a hedge killing problem that would require either adopting a monthly fungicide regime or replacing the hedge with a different species.
Damage to ‘Sunshine’ Ligustrum from pressure washing siding with bleach.
The very next week, another client asked if I would come by her house and take a look at a hedge of ‘Sunshine’ Ligustrum that lines her driveway, whose leaves had “bleached” out, turning from their normal chartreuse to a bronzy white color. This time, having seen similar issues with this particular plant that almost always involved an infestation of Spider or Broad Mites, I figured this was a cut and dry case that would end with a call to her pest control company to come spray the offending bugs. However, though the leaf damage looked similar, I was not able to locate any existing pests or find evidence any had been around recently, rather it appeared the leaves had been exposed to something that “bleached” and burned them. Puzzled, I began asking questions. What kind of maintenance occurs on the plants? Have you fertilized or applied any chemicals recently? Nothing. Then, near the end of our conversation, the client mentioned that her neighbor had pressure washed their house on a windy day and that she was irritated because some of the soap solution had gotten on her car. Bingo. Leaf burn from pressure washing solution chemicals. This time I was guilty of assuming the worst from a pest when the problem quite literally blew in on the wind from next door. Again, the client was relieved to know the plant would recover as soon as a new flush of growth emerged and hid the burned older leaves!
This spring, I’d encourage you to learn from the above situations and the next time you notice an issue on plants in your yard, before you reach for the pesticides, take a step back and think about what the damage looks like, thoroughly inspect the plants for possible insects or disease, and if you don’t find any, consider the possibility that the problem was abiotic in nature! And remember, if you need any assistance with identification of a landscape problem and want research-based recommendations on how to manage the problem, contact your local UF/IFAS Extension office.
The UF/IFAS Extension and FAMU will be bringing the Florida Pest Management Conference to Milton on April 17th. Attend to earn CEUs for your PCO License. Attendance is free and we are currently seeking sponsors at $80 per sponsoring business/organization. For more details and to register, please visit the conference webpage at Northwest Pest Management Conference.
Each Issue, the editors find content of interest from the world wide web and feature it below. This week, our featured video is an interview with noted horticulturist Dr. William C. Welch, about his adventures discovering lost and forgotten rose cultivars across Texas and Louisiana.
Featured Video: Rustling Roses and History: With Texas A&M Extension Horticulturist Dr. William C. Welch, author of ‘Antique Roses for the South’
Camellia sasanqua ‘Kanjiro’ at the South Carolina Botanical Garden
Bi-color Camellia varieties add character to the winter garden
Camellias have been a part of the landscape in the Southeastern United States for over 200 years. They are native to Asia and were introduced near Charleston, South Carolina in 1786. The common name camellia refers to varieties and hybrids of Camellia japonica and to lesser known varieties of C. sasanqua and C. reticulata. The growing conditions in Northwest Florida are well suited for many camellia varieties. Camellias can serve several functions in the landscape including foundation plantings, screens, accent plants, background groupings and hedges. Maximum benefit can be achieved by mass plantings or groupings. Single plants should be focal point in beds rather than randomly placed throughout the lawn. Camellias flower in the fall and winter when their display of colorful blooms is most appreciated. During the remainder of the year their evergreen foliage, interesting shapes and textures, and relatively slow growth make camellias excellent landscape plants. Some camellia growers enjoy competing in flower shows and manipulate the flower buds to achieve larger and earlier flowers. This involves removing competing flower buds and applying gibberellic acid (a plant hormone). Individual cultivars can be selected for size and form ranging from small and irregular to large and upright. Texture and foliage color also differ among the various species and multiple varieties. Midseason flowering varieties that bloom from November through January are best suited for Florida conditions. Warm fall temperatures may prevent early varieties from flowering properly.
Camellia ‘Vernalis Yuletide’ at the South Carolina Botanical Garden
Late-blooming selections may attempt to send out new leaves before the end of the flowering period which results in “bullnoses”. Bullnosing is characterized by poor quality flowers which do not open fully and may even drop while still tight buds. Extended dry periods while in the bud stage can make the condition more likely. While flowering, camellias need 1 inch of water applied each week. Camellias perform best in partially shaded locations which are enhanced by good drainage and air movement. Fertile, acidic soils high in organic matter are preferred. The soil must be well drained because camellias will not grow in wet areas. Do not plant them in areas with a high water table and/or hard pan. This will result in a shallow root system which is more susceptible to injury during dry periods. Camellias should be installed where cold air can move in and out freely, but the area should be protected from strong northwest winds. Plantings under established trees or in areas that has structures to block the wind are usually injured less by cold temperatures. These conditions enable the plants to gradually thaw or warm in the morning before being exposed to direct sunlight. Dense shade may result in sparse foliage and poor flowering. Camellias exposed to full sun may appear yellow-green, but may yield more flowers. Either situation id stressful to the plants and can lead to pest problems. Tea scale is the most common insect on camellias. Scales generally feed on the underside of leaves and may not be noticed until large populations have developed. Symptoms include very small elongated white and/or brown raised “flakes” on the underside of leaves that turning yellowish in color.
Shrubs can serve many purposes in a landscape and have been used in both mass plantings and as accent features. They can include plants that offer colorful blooms, food for pollinators, and screens for less than favorable views.
We tend to think that shrubs will be permanent feature in our landscapes, because many are hardy and adapted to our climate. Like any other plant you may choose for your yard, shrubs may not live forever and there are a wide variety of reasons a shrub may need replacement after years of solid performance.
Let’s use any example from my own yard of the Dwarf yaupon holly, Ilex vomitoria ‘Nana.’ Back in 2001, I planted three hollies, spaced with plenty of room to grow, in a border area of my landscape. The plants grew well forming mounds about 3.5 feet high and 4 feet wide. Since the ‘Nana’ holly is a naturally mounding shrub, it did not require pruning and once established, rainfall supplied needed water.
Yaupon holly with dieback after 17 years in a landscape. Photo by Beth Bolles, UF IFAS Extension Escambia County
Over the past year, several areas of branch dieback have developed in all plants. After finally deciding that the dieback was unattractive enough to warrant plant removal, I began cutting the plants back. I discovered dead interior branches, girdling roots, and some internal stem discoloration. In other words, there are many factors that have led to poor plant performance. Another issue is a large Loropetalum hedge (planted by my neighbor) that shades one side of the plant.
Girdling roots often develop when rootballs have not been properly prepared during installation. Photo by Beth Bolles, UF IFAS Extension Escambia County
What could I have done to help these plants stay healthier for many more years? I could have prepared the rootball better for planting by shaving off the edges or supplied a little fertilizer on occasion in my sandy soil. These practices may have extended the life of the plants for several more years, but they may not have made a difference. Sometimes shrubs decline and die. I am accepting that not everything performs at an outstanding level in our climate. Also, there is an end point for some of my favorite plants in the yard. Some may outlive me while others thrive for a few years or a decade or so.
The bright side of loss of my Yaupon hollies is that I get to plan for a feature for the new year. Maybe something for pollinators and birds to last the next 17 years.
Fatsia japonica, common name Japanese aralia, provides tropical texture to your landscape. That coarse texture is attributed to its large (nearly a foot wide) leaves that are deeply lobed (maple leaf shaped). This shade-loving plant performs well in moist (not soggy) locations. Upright stems originate near ground level usually near the base of older stems. The stems grow to about eight feet tall before bending toward the ground under their own weight.
Even though the foliage of this species is enough to make you want it in your own garden, you will absolutely fall in love with its blooms. Upright clusters of showy, creamy white flowers begin to appear in fall. These little snowballs provide wonderful color to your garden. The shiny, black fruits appear in winter and are prominent for several weeks. The fruit are know to attract birds to the landscape.
A Fatsia japonica specimen in full bloom. Photo Credit: Matt Lollar, University of Florida/IFAS Extension
Fatsia japonica thrives in the shade in slightly acidic, nutrient-rich, moist soil. Older stems become leggy and can be cut back to encourage branching. In the right place, Fatsia japonica is low-maintenance and not typically bothered by pests. It is also known to perform well in coastal landscapes. It fits well in entryways, in containers, or in mass plantings spaced three feet apart.