Citrus is one of the most cherished fruit trees in the Panhandle. Citrus owners are well aware that every year the main damage to their trees come from citrus leafminer (CLM). CLM is a small moth and its larvae feeds between the tissue layers of new leaf growth, causing serpentine mines to form under the leaf cuticle (Fig. 1). The feeding damage results in leaf curling and distortion, and severe infestations of CLM on young trees can retard the growth of trees. Another threat concerning CLM in Florida is that the mines provide an open wound for citrus canker to enter, a bacterial disease that has been found recently in the Florida Panhandle, Georgia, and Alabama.
Most commercial growers deal with CLM in young trees by a soil application of systemic insecticide before the flush season, followed by a foliar insecticide when the systemic drench’s toxicity is declining. Homeowners, however, have limited access to these chemistries. Garden systemic insecticides that include imidacloprid (Bayer’s Tree & Shrub Insect Control™, Merit®, etc.) and dinotefuran (Greenlight Tree and Shrub Insect Control™, Safari®, etc.) are among the few options for CLM control. For the best efficacy, those insecticides should be applied two weeks before the start of the flushing season to allow time for the insecticide to move from the roots into the canopy. To avoid leaching of insecticide away from the root zone, soil applications should be made within a 24-hour period without rain. Citrus trees usually have several flushes per year, depending upon cultivar, climate, and crop load. However, in the Florida Panhandle, most citrus cultivars have two major flushes in May and September.
Importantly, systemic insecticides are only efficient against CLM for small immature trees; therefore, the only products labeled for use against CLM on mature trees are foliar sprays. Horticultural oils or insecticides with spinosad (such as Monterey® Garden Insect Spray) are some options available for homeowners. However, achieving leafminer control with foliar applications on mature trees is challenging due to unsynchronized flushing of trees. Foliar applications should be timed with the appearance of the first visible leaf mines. In any case, be sure to READ THE LABEL and follow all the label directions.
Cultural practices, and non-insecticidal methods.
For isolated trees in a backyard, cultural practices and control through mass trapping are usually sufficient to control CLM and insecticide use is not recommended, especially for mature trees. One of the basic cultural practices is to remove any stems that grow below the bud union or from the rootstock, also called ‘suckers’ (Fig. 2). Those rootstock shoots compete with the scion shoots and are great reservoirs for CLM; removing them will help reducing CLM population. On isolated trees, mass trapping using CLM pheromone provide good results (Fig. 3). The mass trapping method is constituted of a delta trap baited with a lure that emits a large quantity of CLM sex pheromone. CLM males are attracted by the odor and are captured in the delta trap’s sticky liner. Those traps are commonly used by growers to monitor CLM populations, but for homeowners they are sufficient to control CLM on a single tree. This trap and a lure method should protect a single tree for approximately 3 months. Finally, the last option is the use of biological control. Several natural enemies are predators or parasitize CLM. In some case, biological control can reduce CLM populations by 90%. Primary predators of CLM include ants, lacewings, and spiders, as well as a parasitic wasp, Ageniaspis citricola that was introduced into Florida and has become established (Fig. 4).
New growth from the rootstock (called ‘suckers’, red arrow) are a source for CLM infestation and should be removed.
Baited pheromone trap for citrus leafminer (picture Danielle Sprague).
Weeds are basically unwanted plants or plants growing out of place. Proper identification and some understanding of how and why weeds are present in a lawn are important when selecting the best management tactics. All turf weeds can be grouped into one of three life cycles: annual, biennial, or perennial.
Annual: Produces seeds during one season only
Biennial: Produces seeds during two back-to-back seasons
Perennial: Produces seeds over many seasons
Knowing the types of weed previously present in an area also can help one to be better prepared and what control measures to employ in the future.
Weeds may appear in multiple categories, either broadleaf, grass, or Sedges/rushes.
Winter annual weeds in lawn in early spring. Photo credit: Larry Williams
Broadleaves, or dicotyledonous plants, have two cotyledons (seed leaves) when the weed seed germinates.
Appearance: Broad, flat leaves with net-like veins and usually have showy flowers.
Common types: Clover, ground ivy, dandelions, chickweed, plantain, henbit, beggarweed.
Grasses are monocotyledonous plants that have only one cotyledon, or seed leaf, present when seedlings emerge from the soil.
Appearance: Narrow leaves with parallel veins in their true leaves. Hollow rounded stems.
Common types: crabgrass, goosegrass, crowfoot grass, bull grass, annual bluegrass, alexander grass, cogon grass, torpedo grass, and smut grass.
Sedges/rushes. Both favor a moist habitat. Appearance: triangular-shaped, solid stems, while rush stems are round and solid.
Common types: yellow and purple nutsedge and, to some degree, globe, Texas, annual, and water sedge.
One of the first steps in managing weeds is to have a healthy dense lawn/ turf to provide shade that prevents seed germination. Having a healthy lawn depends on turf species selected – making sure you put the right plant and right place. Other factors that influence a heathy turf and a reduced amount of weeds include proper cultural control, fertilizing regularly, mowing at the appropriate height, watering deeply, reducing traffic, pest control, and sanitation. If you only have a few bothersome weeds in your lawn, you may be able to dig them up by hand—but if your lawn is overrun with weeds, you may need to start from scratch. If you decide to start from the beginning, you have a choice ahead of you. Do you want to lay down seed or sod? There are pros and cons to each.
Seed
Pros: Less expensive, more variety
Cons: Takes longer to germinate, can only lay at certain times of year depending on grass type
Sod
Pros: Instant grass, can lay any time of year, requires little maintenance
Cons: More costly, less variety in grass can mean less healthy lawn overall
To prepare the soil after either method, make sure you till it down to roughly 6 to 8 inches.
Supporting information for this article can be found in the UF/IFAS EDIS publications (Weed management for Florida lawns) https://edis.ifas.ufl.edu/publication/EP141 or contact your local Extension Office!
Summer should be the time to relax and enjoy the fruit of all the hard work performed in the landscape over the previous winter and spring. However, there are still some essential tasks that need to be completed during the summer. Perform them in short energy bursts early in the morning or late in the evening.
1. Aerate Your Lawn
If your yard is starting to look weak and thin, even with fertilizing and proper moisture, it may need aeration. Aeration, which is creating channels into your lawn, allows water and nutrients to reach the deep roots of your grass more efficiently.
To test if you need to aerate your lawn, shovel up a patch of grass to a depth of at least four inches. If the layer of thatch is a half-inch thick or higher, your yard would benefit from aeration. There are self-drive aeration machines and tractor-pulled devices you can rent to make quick work of large areas. For smaller areas, simply punching multiple holes with a pitchfork will do the job.
2. Fertilize
Commercial landscape fertilizer applicators must obtain state certification.
Turf grass often displays a yellow color during the mid-summer rainy seasons due to the heavy rains flushing nitrogen away from plant roots. If your lawn is looking sad and yellow, chelated iron can often give a temporary green-up. Iron is not a replacement for nitrogen, but it can work well during our summer rainy season.
If you soil test revealed a potassium or magnesium deficiency, summer is a good time to make the last corrective application. Potassium (K) is an essential macronutrient. Fertilizer bags typically show the percentage of potassium in a product as the third number displayed on the front of the bag (e.g., the “8” in 16-2-8). Potassium acts as a “vitamin” for turf grass, increasing root strength, disease resistance and cold hardiness.
Magnesium (Mg), also a macronutrient, is essential for the production of chlorophyll, necessary for photosynthesis, and also plays a part in the movement of carbohydrates from leaves to other parts of the plant.
3. Don’t Mow Too Short
It’s a natural inclination to want to mow your grass as short as you can, so you have the longest time until you have to mow it again. However, giving your grass a buzz cut every time you mow can hurt your lawn over time.
While some turf grasses can be mowed relatively short, like Bermudas and some Zoysias, most grass types shouldn’t be cut shorter than two-and-one-half to four inches high. Mowing shorter than that can damage the growth point and leave it susceptible to disease and pest infestation. It can also dehydrate the grass and lead to long term damage.
5. Water Infrequently but Deeply
One common mistake made by many is watering too often and too shallow. When only given frequent shallow waterings, grass will begin to grow their roots upwards to take advantage of the small amounts of water, which makes weak and unhealthy. The grass becomes even more dependent on water and very susceptible to disease and insect attack.
Try watering only once or twice a week, but for a considerably longer time so that the water can penetrate deeper into the soil and encourage downward roots. Ideally, each irrigation zone is calibrated to determine the length of time it take to deliver ½ – ¾ inch. Then set the system to run every 3-4 days for that number of minutes. While checking the irrigation delivery system, make sure the rain shut-off device is working and set to the same ½ – ¾ inch.
6. Prevent Mosquitoes
Summer rains on a nearly daily basis lead to lots of standing water. In less than one inch of water, hundreds of mosquitoes can hatch 3 -5 days later. Not only are these blood-sucking pests annoying, but they can also transmit dangerous diseases like West Nile and Zika Virus. Even without disease, their bites are painful and irritating.
To prevent mosquitoes, make sure no standing water is allowed to remain in your yard, either in low points or in empty containers like flower pots or wheelbarrows. Any amount of stagnant water is the perfect breeding ground for mosquitoes. Take a walk around the yard, dumping out water and disturbing the oak and magnolia leaves that are acting a collection cup. Treat birdbaths and water features with floating “donuts” specifically designed to kill mosquito eggs.
While getting tasks done in quick morning trips to the yard, make sure to keep hydrated. Heat exhaustion can happen fast.
Biological control is a pillar of integrated pest management. It may seem a bit daunting the principle is simple. All things in nature have predators including insects. Biological control is simply building a conducive environment for the predators of undesired pests. One animal not often thought of in this capacity is bats. Insectivores by nature, these underutilized creatures have a big impact to your open spaces. Their steady diet of moths (Lepidoptera), beetles (Coleoptera) and flies (Diptera, which includes mosquitoes) reduce insect pressure to your gardens and landscaping.
I know what you are thinking. How effective can they possibly be? Pregnant females consume up to two thirds of their body weight through the summer months while rearing pups. Bats are small but keep in mind that these are not solitary animals. In south Texas, a single large colony consumes enough insects to save cotton farmers an estimated $741,000 per year in insecticides. That is just to illustrate the point as you won’t be able to attract huge colony. There is no reason to believe a smaller colony will not provide similar services in your gardens.
Habitat
Now that your interest is piqued, how can you attract bats to your property? Installing a bat house is the easiest way. They are typically a two foot by one foot structure holding single or multiple chambers in which bats roost. It provides shelter from predation and weather while providing a place to rear pups. Though commercially available they may be built at home with minimal cost. Place the bat house in a location with morning sun at least 12 feet off the ground. Ensure there is enough airflow around the house to keep them cool, but that the structure is watertight. Mount houses on poles next to buildings and you’ll have better success attracting residents. With everything in place, it is time to discover who will most likely be your new neighbor.
photo: Joshua Criss
The Bats of North Florida
Florida is home to 13 species of bats statewide. Of these, 11 may be found in the Panhandle but only 3 are common enough to be routinely seen. The Brazilian free-tailed bat (Tadarida brasiliensis) is the most common. Medium sized with brown fur, they have a long tail, wrinkled cheeks, and roost in man-made structures.
Photo: IFAS
Second most common are Evening bats (Nycticeius humeralis). These dark brown to yellow bats have short ears with a broad hairless muzzle. They are tolerant of other bat species often roosting in tandem with them.
Photo: IFAS
Finally, the panhandle is home to Southeastern Myotis (Myotis austroriparius). Easily the smallest of these bats, they are dull gray to brown with a lighter belly and long hairs between their toes. This species is the bat most likely to eat mosquitoes.
Photo: Jeff Gore, FWC
Finally, the panhandle is home to Southeastern Myotis (Myotis austroriparius). Easily the smallest of these bats, they are dull gray to brown with a lighter belly and long hairs between their toes. This species is the bat most likely to eat mosquitoes.
A Word of Caution
No article on wildlife would be complete without a word of caution. Bats are wild animals and should be treated as such. Never touch a bat on the ground as it most likely is not healthy. Bats do not generally cause issues but have been known to be disease vectors. Call a professional to collect the animal and never bring it into your home.
Bats can be a wonderful tool in controlling pests on your property. Creating habitat can help reduce pesticide need and cost to the homeowner. For more information on bats, see this Ask IFAS document, or contact your local extension agent for additional information on this and any topic regarding your gardens and more.
Use traps crops, such as sunflowers and sorghum, to lure pests away from your crop. Photo by Molly Jameson.
To be a successful gardener, it is important to have an integrated approach to handling obstacles in the garden.
Aphids were lured into this sorghum seed head, which then attracted mealybug destroyer larvae, which are excellent garden predators. Photo by Les Harrison.
These considerations include techniques such as planting disease resistant crop varieties, maintaining proper plant spacing, planting at the appropriate time, monitoring the garden and properly identifying insects and diseases, watering uniformly, and many more cultural and preventative measures that will aid in a garden’s success.
As we transition from the relatively mild and dryer days of late spring into the hot and humid punishing days of summer, we often encounter more and more problems in our gardens.
Insects are commonly one of the main challenges we face, as warm temperatures and high humidity promote the growth and expansion of insect populations. To keep pests in check, it is important to consider all our options. If we turn too quickly to chemical controls, we will often encounter insecticidal resistance over time and our beneficial insect populations will be negatively affected.
One alternative to chemical controls to help combat destruction of our crops is by planting trap crops. Trap crops are plants you grow that the insect pest prefers for food and egg laying over the crops you grow that you plan to harvest. These trap crops attract harmful insects, luring them away from your garden veggies.
Sunflowers can attract leaf-footed bugs away from tomatoes. Hand pick and squish any that you see for better control. Photo by Molly Jameson.
One effective trap crop example, which has proven effective in research studies, is using the combination of sorghum and sunflowers to lure leaf-footed bugs away from your tomatoes. If left unchecked, large clusters of leaf-footed bugs will feed and mate on developing tomato fruit, leaving your tomatoes discolored and distasteful. For tomato growers, it is worth the effort to plant both sorghum and sunflowers about two weeks ahead of your tomato crop. The blooming heads of the sunflowers will lure the leaf-footed bugs in. Hand pick and squish both adults and nymphs off of the sunflowers to help cut back on their populations. As the sunflowers die back, sorghum heads start to emerge, giving you enough time to harvest your tomatoes while the leaf-footed bugs feed on the sorghum panicles.
Another effective trap crop example is to grow blue Hubbard squash at least two weeks ahead of cucurbit crops, such as zucchini, summer squash, or cucumbers. The blue Hubbard squash acts as the trap crop, luring cucumber beetles, squash bugs, and squash vine borers away from the crop.
Buckwheat flowers attract pollinators and predatory insects into the garden. Photo by Janis Piotrowski.
Trap crops are also a great tool for drawing in pollinators and natural predators of insect pests into your garden. For example, sweet alyssum and buckwheat flowers attract wasps and hoverflies. The wasps will lay their eggs on caterpillar pests, and when the eggs hatch, the wasp larvae eat the caterpillars as they mature. Hoverflies will lay their eggs on the leaves of the trap crops, which will hatch and feed on mealy bugs and aphids. Additionally, bees will be attracted to the trap crop flowers, introducing more and more pollinators into your garden.
When it comes to being a successful gardener, it is important to have an integrated approach. When cultural and preventative gardening techniques are combined with biological control techniques, such as trap cropping, your garden will be more resilient to pests and diseases, and you will be less reliant on chemical control methods, which should be seen as a last resort.
We often think of plant pests to be only insects. However, plant pests can also be fungal and bacterial diseases, weeds, and even rodents. That’s right, rodents, like squirrels, mice, and rats! One particularly annoying rodent pest of the garden is the roof rat (Rattus rattus, a.k.a. citrus rat, fruit rat, black rat, or gray rat). Roof rats are native to southern Asia. This is the same species that was responsible for carrying the bubonic plague around the world. Roof rats are the most detrimental rodent pest to fruit crops in the state of Florida. In addition to fruit crops, they feed on stored animal and human food. Roof rats live in attics, soffits, walls, and outbuildings. They also chew through wires, pipes, and walls. Roof rats damage some fruit crops (like citrus and melons) by first creating a half dollar sized hole, then they hollow out the fruit. In crops without a rind or peel, like peaches and tomatoes, they just eat large chunks.
Roof rat damage to tangerines. Photo Credit: Matt Lollar, University of Florida/IFAS Extension – Santa Rosa County
Adult roof rats are 12-14 inches long with tails longer than their body length. In Florida they have been identified in three color phases: black back with gray belly; gray back with light gray belly; and brownish gray back with a white or cream colored belly. Other than fruit damage, evidence of infestation includes 1/4-1/2 inch long droppings and rub marks left along travel trails. Roof rats will travel up to 150 yards from their den for food and water. They breed year-round and have litters of 5-8 pups with a gestation period of only 21 to 23 days.
An adult roof rat. Photo Credit: Alabama Cooperative Extension System
A well-thought-out integrated pest management strategy is needed to control and potentially prevent roof rats on your property. Integrated pest management is a strategy consisting of multiple tactics to control a pest. These tactics include scouting (looking for evidence of the pest population); prevention; trapping and exclusion; biological control such as predators; and rodenticides and repellants.
Prevention – Roof rats are good climbers and swimmers. It is important that fruit trees are planted away from the house, fences, and outbuildings. Make sure to prune fruit trees away from these structures if they can’t be removed or transplanted to another location. Also prune branches from touching the ground to help prevent rats from using trees for cover. Sheet metal (18-24 inches wide) can be loosely wrapped around the tree trunk to keep rats out of the tree.
Trapping – Rat traps can be placed in several strategic locations. Traps (triggers facing down) can be attached to the trunks of trees. Traps can also be attached to the stringer boards on a fence. Make sure that traps are only set from dusk to dawn to avoid killing non-target species like birds and squirrels. Leave traps in place for at least a week before moving them because roof rats are cautious of new objects.
Rodenticides & Repellants – Poisons should only be used after all other control methods are exhausted. Most products are very toxic to humans, pets, and wildlife. If used outdoors, poison baits must be placed in tamper-resistant bait stations.
Biological Control – Rat snakes and king snakes are good natural predators for roof rats. If you have more open spaces you may consider building a barn owl house. Barn owls and hawks are also natural predators. You may also consider getting a farm cat to help control the population. Cats will kill juvenile rats, but have trouble catching adult rats.
Hopefully you will never have to encounter roof rats or other rodents invading your yard and house. However, if they do come around more information is available in the publication “Pests in and Around the Southern Home“.
