Mosquito Control in Your Landscape

 

A natural disaster such as Hurricane Michael can cause excess standing water which leads nuisance mosquito populations to greatly increase. Floodwater mosquitoes lay their eggs in the moist soil. Amazingly, the eggs survive even when the soil dries out. When the eggs in soil once again have consistent moisture, they hatch! One female mosquito may lay up to 200 eggs per batch . Standing water should be reduced as mush as possible to prevent mosquitoes from developing.

You should protect yourself by using an insect repellant (following all label instructions) with any of these active ingredients or using one of the other strategies:

  • DEET
  • Picaridin
  • Oil of lemon eucalyptus
  • Para-menthane diol
  • IR3535
  • An alternative is to wear long-sleeved shirts and pants – although that’s tough in our hot weather
  • Wear clothing that is pre-treated with permethrin or apply a permethrin product to your clothes, but not your skin!
  • Avoid getting bitten while you sleep by choosing a place with air conditioning or screens on windows and doors or sleep under a mosquito bed net.

Now let’s talk about mosquito control in your own landscape.

Let’s first explore what kind of environment in your landscape and around your home is friendly to the proliferation of mosquitoes. Adult mosquitoes lay their eggs on or very near water that is still or stagnant. That is because the larvae live in the water but have to come to the surface regularly to breeze. The small delicate larvae need the water surface to be still in order to surface and breathe. Water that is continually moving or flowing inhibits mosquito populations.

Look around your home and landscape for these possible sites of still water that can be excellent mosquito breeding grounds:

  • bird baths
  • potted plant saucers
  • pet dishes
  • old tires
  • ponds
  • roof gutters
  • tarps over boats or recreational vehicles
  • rain barrels (screen mesh over the opening will prevent females from laying their eggs)
  • bromeliads (they hold water in their central cup or leaf axils)
  • any other structure that will hold even a small amount of water (I even had them on a heating mat in a greenhouse that had very shallow puddles of water!)

You may want to rid yourself of some of these sources of standing water or empty them every three to four days. What if you have bromeliads, a pond or some other standing water and you want to keep them and yet control mosquitoes? There is an environmentally responsible solution. Some bacteria, Bacillus thuringiensis ssp. israelensis or Bacillus sphaericus, only infects mosquitoes and other close relatives like gnats and blackflies and is harmless to all other organisms. Look for products on the market that contain this bacteria.

 

For more information:

Mosquito Repellents

UF/IFAS Mosquito Information Website

 

Protecting Our Pollinators in the Landscape

Protecting Our Pollinators in the Landscape

European honey bee. Photo credit: UF/IFAS.

Bees, butterflies and other insects play important roles as pollinators in our environment. Over 50 major crops in the United States and at least 13 crops in Florida depend on honey bees. Many native plants in natural areas also depend on insect pollinators for reproduction. In Florida, over 300 bee species play a role in pollination!

Many factors affect the health of our pollinators. One of those factors we can easily control in our own landscapes is exposures to pesticides. How are bees and other pollinators exposed to pesticides? Here are some of the major routes:

  • Drift of pesticides sprayed in breezy/windy conditions
  • The erosion of contaminated topsoil blowing in the wind
  • Direct feeding on pollen and nectar of treated plants
  • Contact with pesticides that have blown onto plant surfaces
  • Contact with water transpired by leaves of treated plants
  • Pesticides that move down through the soil to affect ground dwelling bees and other insects

Did you know that bees become statically charged when they fly causing particles in the air to attract to them?

What are some ways that we can reduce the risk of exposure to pollinators in our landscapes?

  1. Use integrated pest management principles to reduce the incidence of pests and their impacts.
  2. Avoid treating areas containing flowering weeds/plants with insecticides. If you must treat your lawn with an insecticide, and it contains flowering weeds, mow the lawn and remove the flowers just before applying the insecticide.
  3. If you must apply a systemic insecticide to your lawn, leave a buffer strip of several feet between the lawn and the border of landscape beds with flowering plants. This will prevent the flowering plants from up taking the systemic product.
  4. Postpone any insecticide treatment until after all blooms have fallen from flowering ornamentals. Never apply an insecticide to blooms or flowering plants.
  5. Avoid the use of neonicotinoids as this class of insecticides can be more toxic to bees than other classes of insecticides. There are many effective alternatives.

Bee friendly to our pollinators!

 

For more information:

Minimizing Honey Bee Exposure to Pesticides

Creating and Maintaining Healthy Pollinator Habitat – Xerces Society

 

Recent Weather Fueling Fungi

Florida’s panhandle has received quite a bit of rain this summer. In the last three months, depending on the location, approximately 15 to 35 inches of rain have come down, with the western panhandle on the higher end of that range. In addition to the rain, we all know how hot it has been with heat index values in the triple digits. And who can forget the humidity?! Well, these weather conditions are just the right environmental factors for many types of fungi, some harmful to landscape plants, most not.

In the classification of living things, fungi are divided into their own Kingdom, separate from plants, animals, and bacteria. They are actually more closely related to animals than plants. They play an important role on the Earth by recycling nutrients through the breakdown of dead or dying organisms. Many are consumed as food by humans, others provide medicines, such as penicillin, while some (yeasts) provide what’s needed for bread and beer. However, there are fungi that also give gardeners and homeowners headaches. Plant diseases caused by various fungi go by the names rusts, smuts, or a variety of leaf, root, and stem rots. Fungal pathogens gardeners may be experiencing during this weather include:

  • Gray leaf spot – This fungus can often show up in St. Augustine grass lawns. Signs of this fungus include gray spots on the leaf (very descriptive name!). This disease can cause thin areas of lawn and slow growth of the grass.

Gray leaf spot on St. Augustine grass. Credit: Phil Harmon/UF/IFAS.

 

  • Take-all root rot – This fungus can attack all our warm-season turfgrasses, and may start as yellow leaf blades and develop into small to large areas of thin grass or bare patches. The roots and stolons of affected grasses will be short and black.

 

Signs of take all root rot. Credit: UF/IFAS.

Powdery mildew – This fungus can be found on many plants, from roses to cucumbers. It looks like white powder on the leaves and can lead to plant decline.

  • Armillaria root rot – This fungus can infect a variety of landscape plants, including oaks, hickories, viburnums, and azaleas. Symptoms can include yellowing of leaves and branch dieback, usually in adjacent plants. Old hardwood stumps can harbor this fungus and lead to the infection of nearby ornamentals.

Because fungi are naturally abundant in the environment, the use of fungicides can temporarily suppress, but not eliminate, most fungal diseases. Therefore, fungicides are best used during favorable conditions for the particular pathogen, as a preventative tool.

Proper management practices – mowing height, fertilization, irrigation, etc. – that reduce plant stress go a long way in preventing fungal diseases. Remember that even the use of broadleaf specific herbicides can stress a lawn and exacerbate disease problems if done incorrectly. Since rain has been abundant, irrigation schedules should be adjusted to reduce leaf and soil moisture. Minimizing injury to the leaves, stems, and roots prevents stress and potential entry points for fungi on the move.

If you think your landscape plants are suffering from a fungal disease, contact your local Extension Office and/or visit the University of Florida’s EDIS website at http://edis.ifas.ufl.edu for more information.

My Tree Has Tumors

As oak trees are now fully leafing out and people start hanging out in the shade of the canopy, many of you are noticing strange growths on the branches. They look like potatoes, spiky cones and fuzz balls on the leaves and stems.  Don’t worry.  It’s just a harmless wasp that chose that tree to create a nursery for her young.

Galls are abnormal plant growth or swellings comprised of plant tissue. Galls are usually found on foliage or twigs. These unusual deformities are caused by plant growth-regulating chemicals produced by tiny wasps. The chemicals produced by these insects interfere with normal plant cell growth.

The life cycles of the various gall-forming wasps are highly variable. Two or more years are required for gall wasps that develop in woody twig galls to reach maturity. Gall-forming wasps usually overwinter as adults in protected places away from the host tree. As the buds break in the spring and the leaves begin to expand, these small wasps start to lay their eggs in expanding plant tissue. During the egg-laying process or early larval-feeding period, specialized body glands secrete growth-regulating chemicals that interact with certain plant chemicals to produce these abnormal growths.

After a brief period of cell growth, gall development stops completely. Once these galls are formed, they do not continue to use nutrients from the host plant.  The insect is confined within “its house” and feeds only on gall tissue during the remainder of its development. The galls provide shelter, protection, and food for the immature wasps. Inside a gall, the larvae are surrounded by tissues rich in nutrients

There are a variety of gall-forming species of small wasps that commonly infest oak, Quercus spp ., trees. Galls generally are aesthetically objectionable to homeowners who find them unattractive and fear that galls will cause damage to the health of their oak trees.  Most leaf galls on oak cause little or no harm to the health of a tree. However, twig or branch galls may cause injury by distorting branch development in a heavily infested tree.

Chemical control is seldom suggested for management of leaf galls on oak. Cultural methods of control may be effective in reducing the impact of these insects. Some fallen leaves may harbor various life stages of gall-producing pests. Therefore, it may be useful to collect and destroy all infested leaves. Some of these pests overwinter in twigs and branches of oak. Where such woody galls are detected, prune and destroy the infested plant material when the galls are small and have just started to develop.  But, remember every bug needs a home!

All photos by Eileen Buss, UF Entomologist

Benefit from Beneficial Insects

Adult Ladybug. Photo Credit: James Castner University of Florida

A number of summers ago, I noticed whiteflies on a confederate rose plant in my landscape. I considered using an insecticide to control the whiteflies but decided against doing so after taking a closer look. What I found was a population of ladybugs – eggs, larvae, pupae and adults.

Ladybug adults and larvae eat whiteflies, as well as other soft-bodied insects such as aphids. So, I waited to see what would happen.

At first I was seeing mostly adult whiteflies, which look like tiny white moths. Adult whiteflies mate and then lay eggs on the underside of leaves. The eggs hatch into flat translucent scale-like nymphs that suck the “juice” from the underside of the leaves.

Eventually, some of the leaves developed a black coating called sooty mold. As certain insects (primarily aphids, some scales and whiteflies) feed, they excrete plant sap that coats the leaves. Sooty mold then grows on this sugary sap. It’s not a pathogen. It just makes the leaves look ugly.

Knowing that the whiteflies would not kill the confederate rose, I was willing to tolerate the sooty mold and allow the ladybug population to build.

Allowing whiteflies to live on your plants may not always be the best option. But in order to have beneficial insects in your landscape, there must be some “bad” insects for them to eat.

Insects such as ladybugs, lacewings and praying mantises eat many pest insects. Encouraging these beneficial insects can allow you to reduce the amount of pesticides applied.

It’s important to learn to recognize the adult and immature stages of these beneficial insects. Ladybugs have larvae that look nothing like

Ladybug larva. Photo credit: Aristizabal University of Florida

the adults. Some ladybug larvae look like small orange and black alligators. Others may resemble mealybugs. Many gardeners that would never kill adult ladybugs mistake their larvae as pests and kill them with insecticides.

The following UF/IFAS Extension website will help you learn to recognize many of our beneficial insects. http://edis.ifas.ufl.edu/topic_beneficial_insects

Once you find beneficial insects in your landscape, reduce or eliminate the use of insecticides. When an insecticide is needed, use environmentally friendly options such as insecticidal soaps, horticultural oils and products that contain Bacillus thuringiensis (Bt).

Sometimes a heavy stream of water from a water hose is all that is needed to remove pest insects from plants and reduce their numbers to an acceptable population.

Remember, leaving a few pest insects is a great way to attract beneficial insects. Tolerating a minor infestation and a little plant damage will benefit the helpful insects, your pocketbook and the environment.