Landscape Architect Articles

Pest Problems and Solutions02-01-09 | News

Pest Problems and Solutions

Matthew Doyle, assistant editor

Applying an insecticide in the neonicotinoid family via root-drench is an effective whitefly preventative measure. Foliar application is also permissible, however, simultaneous use of the two techniques isn?EUR??,,????'?????<Image Courtesy Miami-Dade County Parks and Recreation Department

Pest control is becoming ever more complicated these days. Definitions of humane treatment are ever stricter. Environmental concerns limit chemical options. Finally, invasive species benign in their country of origin become an immense threat in your predator-free landscape. LCN has talked to several landscape professionals around the country seeking their solutions.

Ficus hedges are extremely popular in the Miami-Dade area, with devastating results. The fig (ficus) whitefly (Singhiella simplex) produces approximately eight generations a year according to Assistant Professor Catharine Mannion of the University of Florida?EUR??,,????'?????<

Whitefly Plagues Miami

The Miami-Dade County Parks and Recreation Department has a special tax division within its ranks, headed up by Gil Delgado. Their primary pest challenge of late has been the fig (ficus) whitefly, Singhiella simplex.

The problem was initially discovered near the Miami River in September of 2007 according to the landscape professional. While unsure of the method of arrival, a private ship traveling the river from the insects?EUR??,,????'?????<
Threat: The life cycle of the bug is one month, resulting in approximately eight generations per year according to Assistant Professor Catharine Mannion of the University of Florida?EUR??,,????'?????<

Proper application of root-drench insecticides should provide control for at least four to six months, although inspection three months after application is recommended. Control is therefore possible, but the associated cost remains a challenge. Biological control measures, particularly ladybugs and parasitoid wasps, are being attempted. However, University of Florida Extension Agent Henry Mayer notes overnight results aren?EUR??,,????'?????<Courtesy Miami-Dade County Parks and Recreation Department

The prevalence of ficus in the Miami area has resulted in massive damage. Hedge examples of the plant are destroyed in two to three weeks according to Delgado, and the numbers involved are striking. The landscape professional claims one 2.5-mile stretch under his watch is planted at 24 to 30 inch intervals. This works out to about 5,000 plants worth $422,400 to $528,000 assuming an $80 to $100 replacement cost per individual. The common nature of this situation leads the superintendent to estimate regional damages in the millions, not including nurseries.

Solution: The best option discovered so far is a preventative root drench with insecticides in the neonicotinoid family. Foliar application is also viable, although it is not recommended the two techniques be combined. However, care must be taken to avoid killing natural enemies like beetles, parasitoids, and lacewings. According to Miami-Dade County Extension agent Henry Mayer of the University of Florida, ladybugs and parasitoid wasps are the primary organisms utilized for biological control. However, overnight results aren?EUR??,,????'?????<

Over 3,000 oleanders line the fields, stadium perimeters and fence lines of the Home Depot Center. The residences bordering this fence line make pest damage all the more visible and control that much more essential. This is a challenge considering the first symptoms were observed in 2007, and by 2008 roughly 1,000 individuals had been lost. Image Courtesy Home Depot Center

Oleander Scorch and Fungi Fury

35-year green industry veteran Robert Adams is charged with keeping pests in check as head groundskeeper of what has been called ?EUR??,,????'?????<

To breakup the brick common throughout the facility, over 3,000 oleanders line the fields, fence lines and stadiums. However, these ornamentals also attract the glassy-winged sharpshooter and other carriers for the bacterium Xylella fastidiosa. It?EUR??,,????'?????<

The superintendent has attempted spraying, but claimed little effectiveness as a result of the glassy-winged sharpshooters mobility. He sees the only viable approach as replacement, in this case with Carolina cherry. Infected oleanders are cut to within six inches of the ground, which provides up to six months of additional life. At the same time, the cherries are planted between the diseased individuals. While cutting to six inches effectively means double-duty, Adams feels the extra growth they get is worth it. Image Courtesy Home Depot Center

The insect transmits the bacteria through its saliva as it feeds. According to the University of California Riverside, it can consume up to 10 times its weight in fluids and lives for six months. The same source claims an ability to fly up to a quarter-mile and survive temperatures as low as 20 degrees Fahrenheit. These factors make it an extremely effective carrier.

As the bacteria multiplies, it produces a gel that clogs the xylem and with it nutrient and water flow. Leaves turn yellow and brown before falling off. The whole plant is eventually defoliated and dies. According to the superintendent, attempts at spraying have been ineffective as a result of the pests mobility. Thus, he doesn?EUR??,,????'?????<

While the facilities use of reclaimed water conserves a valuable resource, it also creates pest challenges. The superintendent claims the high salinity and nitrate levels encourage the growth of several turf fungi. A resulting preventative and curative fungicide program costs nearly $100,000 annually. Daily field inspections are also utilized while tissue and soil samples from trouble spots are immediately sent to Ag Source Harris Laboratories, Turf Diagnostics or Soil and Plant Laboratory for analysis.

Adams is thereby limited to a replacement course of action. Symptomatic plants are initially cut to within six inches of the ground before allowing them to re-grow. As always when dealing with bugs, clippings should be double bagged for disposal and tools cleaned. This technique allows for up to six months of additional growth from some infected individuals.

Meanwhile, Carolina cherries are planted between the affected oleanders. This fills space and gets an eventual replacement growing. While it effectively doubles his labor, the facility manager feels it?EUR??,,????'?????<
The cost of this approach varies with the replacement plants?EUR??,,????'?????<
The landscape professional also noted that flower coloration seems to affect the infection process. White and pink blooming varieties appear to be particularly vulnerable, with some only lasting four months, while he had gone a year with red individuals symptom free. However, these plants recently developed the disease and are expected to die. Well he didn?EUR??,,????'?????<
Turf Fungus Issues: The reclaimed water used at the center exhibits high nitrate and salt levels. According to the groundskeeper, this exacerbates fungus problems.

The most notable example is the soccer field, where he claims the high nitrogen levels have made the turf susceptible to phytophthora, Fusarium blight, grey leaf spot and Pythium blight fungi?EUR??,,????'?????<

The Landscape Superintendent has observed a difference in the impact of Pierces disease dependent on flower color. The white and pink blooming oleander varieties develop symptoms rapidly and succumb within four months. However, the red-flowering individuals were symptom free until recently. While careful to point out no scientific basis for it, Adams speculated some degree of resistance might be present in these plants. Images Courtesy Home Depot Center

Initial treatment only consisted of a curative program. While this helped, in late 2006 through 2007 the decision was made to add a preventative component. Fungicide expenditures were nearly $100,000 in 2008 as a result, with the figure in 2007 being around $70,000.

Adams estimates the absence of these nitrogen and ammonia issues would result in the fungicide budget dropping to 1/3 or 1/2 of its present value. While the West Basin Water District is working on reducing nitrate and salt levels in their reclaimed water, so far the superintendent hasn?EUR??,,????'?????<
The fungicide program is teamed with an aggressive inspection program so the substantial outlay is used as efficiently as possible. Fields are inspected daily, and if something doesn?EUR??,,????'?????<
Other Pest Challenges: Two other problems remain. The first is Cuban laurel Thrips, which attack the numerous ficus?EUR??,,????'?????<
A final issue that?EUR??,,????'?????<

Neuburg supports a catch-and-relocate approach whenever possible, raccoons included. ?EUR??,,????'?????<

Exotic Pest Threat: Coral Snakes

The University of Texas at Brownsville has a fairly unique problem: venomous snakes. Both Copperhead and Coral snakes are native to much of the western U.S., Texas included, and occasionally wander on to campus. If left untreated, bites from both animals have the potential to be fatal. Even if successfully treated, the school could end up paying for an emergency room visit followed by weeks of hospitalization. There?EUR??,,????'?????<
With such a serious pest threat to deal with, landscape professional Lawrence Neuburg takes preventative measures seriously. The primary strategy is to open up all areas of the campus, thereby eliminating snake-friendly habitat. These animals depend on heavy cover to prevent becoming prey-items themselves, and therefore avoid open areas. Extra mowing around buildings and walkways ensures snakes are discouraged from passing through. While it ups fuel and labor expenses in a tough economy, the leader describes these costs as ?EUR??,,????'?????<
If a snake is spotted, a capture-and-relocate approach is utilized. While this incurs more extra costs, Neuburg feels it worthwhile. ?EUR??,,????'?????<

A Coral snake was recently found near the student union building and captured for relocation. Primary management strategies involve extra mowing around all walkways and buildings. This creates open areas where the snakes are vulnerable to predators, which the reptiles consequently avoid. Plans are in the works to harvest life-saving anti-venom from the captured pests. images courtesy The Collegian

From Life Threatening to Life-Saving: The facility is working toward an agreement with the Brownsville city zoo to handle captured snakes. While they would still be relocated, the reptiles would also be used to harvest venom. This could then be sythesized to produce lifesaving anti-venom.

According to Nueburg, there?EUR??,,????'?????<
As a result of these efforts, the grounds department at the University of Texas at Brownsville may transform a very serious pest problem into a lifesaving service of the institution.