Fruit Thieves: Roof Rats

Fruit Thieves: Roof Rats

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.

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 years.

An adult roof rat.

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“.

Fall Grass-Eating “Worms”

Fall Grass-Eating “Worms”

Brown patch in grass

Chewing caterpillar damage on St. Augustinegrass Photo by: Steven Arthurs, UF

Tropical sod webworm larvae are destructive pests of warm season turfgrasses in the southeastern U.S. especially in the fall.  Commonly referred to as a worm, they are truly caterpillars, the larvae of a moth. Larval feeding damage reduces turfgrass aesthetics, vigor, photosynthesis and density, which is very evident on finer-bladed grasses such as bermudagrass and zoysiagrass. Feeding damage is possible on all grass types however. Adults, a dull brown colored moth about ¾ inch long, rest in sheltered and shrubby areas during the day and are active at dusk.  Females deposit clusters of 10-35 eggs on the upper surface of grass blades.  The eggs hatch in 3-4 days and develop from a 1 mm long caterpillar to one over 11 mm long through six instars within 21 to 47 days, depending on temperature.  Larval feeding occurs at night, leaving the grass looking ragged, shortened and missing.

Small green caterpillar in grass

Sod webworm on soil surface
Photo by: Steven Arthurs, UF

 

Control should be against damaging larvae, not the flying moths.  However, insecticidal soap applications to moth harboring areas can reduce re-population frequency.  Soil-drenching soap flushes can be used to find the caterpillars, especially in dry and hot grass areas.  Bacterial-based insecticides, such as Bt, Bacillus thuringiensis var. kurstaki or Spinosad, will control sod webworm caterpillars without impacting beneficial species as long as they are applied with each flush of grass growth.

 

Fall armyworms are also active when the weather turns cooler. They feed any time of the day or night, but are most active early in the morning or late in the evening.  The 1 ½ inch long gray and white moth lays about 1,000 eggs in multiple masses on any vegetation.  Two to 10 days later, the small caterpillar hatches and begins to grow to nearly 2 inches long over a two week period.  The fall armyworm is easily recognized by its dark head marked with a distinct pale-colored inverted Y and the long black stripe running along each side of its body.  These aggressive feeders “march” rapidly across grassed areas consuming every above-ground plant part.  While bacterial-based insecticides will reduce the numbers, control of armyworms usually requires synthetic insecticides.

Striped caterpillar with Y marking on the head

Armyworm
Photo by: Jim Castner, UF

 

The good news is that grass “worms” can be controlled and the blades will grow back.  The damage may be devastating to see, but usually not a permanent problem.

The North Florida Vegetable Gardening Guide

The North Florida Vegetable Gardening Guide

As you garden this fall, check our the North Florida Vegetable Gardening Guide, compiled by UF/IFAS Leon County Extension.

As you garden this fall, check out the North Florida Vegetable Gardening Guide, compiled by UF/IFAS Leon County Extension.

 

Getting into vegetable gardening, but don’t know where to start?

Even experienced gardeners know there’s always more to learn. To help both beginners and advanced gardeners find answers to their questions, the UF/IFAS Leon County Extension Office put together the North Florida Vegetable Gardening Guide. It incorporates multiple resources, including articles, planting calendars, photos, and UF/IFAS EDIS publications.

The North Florida Vegetable Gardening Guide covers the many aspects of vegetable gardening, including how to get started, site selection, insects and biodiversity in the garden, soil testing, composting, cover crops in the garden, irrigation, and more.

You can click here to view the digital version of the guidebook. We also have physical copies of the guide available at the UF/IFAS Leon County Extension Office (615 Paul Russell Rd., Tallahassee, FL 32301).

Happy fall gardening!

Controlling Cogongrass

Controlling Cogongrass

Over the last decade or so, the Panhandle has been overrun, and I don’t just mean by the summer beach traffic.  Rather, by an aggressive, exotic perennial grass that quickly displaces all native species, is not useful as a forage to wildlife or livestock, can spread by roots or seeds, and has no natural enemies.  If you own property in the Panhandle or spend any amount of time on its roads, chances are you have become acquainted with this worst of invasive species, Cogongrass (Imperata cylindrica).

A native of Southeast Asia, cogongrass was introduced into the US in 1912 around Mobile, AL as a hitchhiker in orange crate packing.  Then the 1920s, 30s, and 40s, it was intentionally introduced from the Philippines into other Gulf Coast states, including Florida, as a potential pasture forage for livestock.  Since then, cogongrass has become one of the most economically and ecologically important invasive species in the US and worldwide, infesting nearly 500 million acres and is now found on every continent.

Cogongrass in Calhoun County, FL. Photo courtesy of Daniel Leonard.

Cogongrass is easily identified in late spring, when the grass throws easily spotted fluffy, white-colored seedheads above the mats of grass beneath.  Additionally, patches of cogongrass are almost always noticeably circular in nature, radiating out indefinitely from the initial infestation.  A closer inspection of the grass will reveal light green leaves up to 4’ in length, with an off-center, silvery colored midrib (the primary leaf vein that runs from the base of the leaf to the tip) and serrated leaf edges.   Underground, cogongrass exhibits a dense underground root system that can reach as deep as 4’.  This feature is the primary reason cogongrass outcompetes other plants, withstands any drought, fire, or soil condition thrown at it, aids in its resistance to herbicide activity, and generally makes it very difficult to manage.

The first step in managing cogongrass is prevention.  If your property or the property you manage doesn’t have cogongrass, do everything you can to keep it that way.  While the species can spread distances through seed dispersal, it is much more frequently moved around by fragmented rhizomes hitching a ride on equipment.  If you or a contractor you’ve hired are working in or around an area with cogongrass present, avoid disturbing it with equipment and be diligent in monitoring the site for outbreaks following the job’s completion.

If you find cogongrass on your property, effectively eradicating it requires patience, persistence, and several years’ worth of herbicide applications.  Currently, of the hundreds of herbicides available for purchase, only two chemistries have been proven to be very effective in destroying cogongrass, impazapyr (Arsenal, Stalker, etc.) and glyphosate (Roundup, Cornerstone, etc.).

  • Imazapyr is an extremely effective non-selective, residual herbicide that controls a wide variety of weed species, including cogongrass. Just one or two applications of imazapyr can provide 18-24 months of effective cogongrass control, with follow up treatments required as needed after that.   However, Imazapyr has a major downside that limits its use in many settings.  Because it is a non-selective herbicide with significant soil residual activity, it cannot be used around the root zones of desirable plants.  Oaks, other hardwood trees, and most landscape plants are especially sensitive to imazapyr.  This herbicide is best limited to use in fields, waste/fallow areas, natural areas, and monoculture pine plantations – it is not appropriate in most residential and commercial landscapes.
  • The other option, glyphosate is a non-selective herbicide with no soil residual activity. It is often a better option where severe injury or death of desirable hardwood trees and ornamental plants cannot be tolerated.  However, due to its lack of residual soil activity, glyphosate applications on cogongrass patches will need to be repeated on an annual or biannual basis for up to five years for eradication of the infestation.

*Regardless of which herbicide you choose, controlling cogongrass is a multi-year affair requiring diligence and patience. 

For more information on cogongrass and for specific herbicide recommendations and application rates/timing for your site, please contact your local UF/IFAS County Extension Office.

 

Fall Preparation in the Garden!

Fall Preparation in the Garden!

Carrots need enough space so as not to compete for light, nutrients, or moisture. Photo by Full Earth Farm.

Photo by Full Earth Farm.

Yes, that’s right! We made it through the hottest part of the year and we are looking ahead to fall just around the corner!  I am excited to be discussing September and what we can do to prepare for fall in the garden.  As the nighttime temperatures start to cool down, we are given many more options.

For annual color plantings in September, try Ageratum, Celosia, Zinnias, and Wax Begonia to add fall color to your landscape.  Bulbs will also add color, texture, and pattern to a bed.   If you have some extra space, a variety of elephant ears could really accent a bed or you could always go with the classic calla, narcissus or zephyr lily.  Popular vegetables to plant in North Florida in September are broccoli, carrot, cabbage, and collards. See Vegetable Gardening in Florida This is also the time of year to establish strawberry plants.  Some great herbs to get started are Mexican tarragon, mint, rosemary, and basil.

Strawberries growing on "plastic" to protect them from water splashed fungal spores found in soil. Image Credit: Matthew Orwat UF/IFAS Extension Washington County

Image Credit: Matthew Orwat UF/IFAS Extension Washington County

There are many things that can be done in your lawn during September.  Monitoring your lawn for its health and potential insect pests is important this time of year.  Common insects to scout for are fall armyworms, chinch bugs, mole crickets, and sod webworms.  The last fertilizer application should be done by the middle to end of September.  Make sure you choose a fertilizer with little to no phosphorus unless a soil test shows differently.  To maintain a healthy lawn, avoid weed and feed products and only apply herbicides in areas with high infestations of weeds. Weed and feed products are not recommended because the timing of when to fertilize and the timing of the weed killer is not always the same. The best management practice is to use a separate treatment for weeds and when possible spot treat weeds.

If you already have bulbs in your landscape from previous growing seasons, this is the time to divide and replant those that are big.  You can also add organic matter to new planting areas. Continue working on your vegetable plants and prepare them for either transplants for a fast start, or plants seeds for more variety.  Throughout your landscape, it is important that plants are getting the right amount of water as we go in and out of wet and dry weather this time of year.

October will be here before we know it in just a couple of weeks. Look out for the next article to come.  We will be getting into the cooler nights and more options for planting vegetables and herbs!

Be Patient with Key Limes

Be Patient with Key Limes

Growing Key Limes in the home landscape is not only a fun and unique addition, but is also delicious – any way you slice them.

The key lime, Citrus aurantifolia, originated in southeast Asia. Genetically speaking, the key lime is likely a tri-hybrid cross between the “odd ball fruits”, known as citron, pummelo and a microcitrus species, Citrus micrantha. There is little commercial key lime production nowadays in Florida, but the fruit remains a very popular landscape option.

The key lime is a small, bushy tree that makes harvest and pruning a breeze. Like most citrus, it’s self-pollinating. The key lime is also an ever-bearing fruit, so there is no real seasonal harvest. The tree could technically bloom any month of the year. There are very few varieties, as trees mostly come from true seed or air layering.

Key Lime fruit at various degrees of ripeness. Photo courtesy of Ray Bodrey, UF/IFAS Extension Gulf County.

Climate is an important factor when deciding to plant a key lime. They are sensitive to cold temperatures, especially below freezing. For the Panhandle, it’s wise to keep key lime trees as patio citrus. In other words, keep the trees in pots so that they can be moved indoors for protection during the winter months.  In the ground, trees should be planted in an area where there is a significant wind block.  Once a few years have passed and tree has become more mature and acclimated to the environment, they may be able to survive on their own, though it is recommended to cover the tree under sub-freezing temperatures. However, it is important to remember that sunlight is a catalyst for citrus fruit production, be sure to plant the tree in an area with full sun.

The usual suspects of citrus insect pests apply to the key lime also. Citrus leaf miner and mites are the most common culprits. Horticultural and insecticidal oils will certainly help to combat these threats. For planting, key lime is well adapted to a variety of soil conditions in Florida. Be sure to water newly planted trees every other day for the first week and then one to two times a week for the first couple of months. Water periodically after that, making sure the soil doesn’t stay completely dry for long periods. A 6-6-6 fertilizer works great for the key lime. Please follow the fertilizer schedule found in the UF/IFAS EDIS publication, “Citrus Culture in the Home Landscape” by Robert E. Rouse and Mongi Zekri: https://edis.ifas.ufl.edu/pdf/HS/HS132/HS132-11822781.pdf

A final interesting thing about the key lime is the ripening stages of the fruit. Because key limes are ever-bearers, blooms can develop at sometimes widely varying times. This causes an uneven development of fruit across the tree. Be sure to wait until the fruit turns begins to turn yellow before harvest. That’s when it’s mature to eat!  Fruit can be stored for up to a week in the fridge or can be juiced and stored in the freezer for later use.

Please contact your local county Extension office for more information. Happy Gardening!

Information for this article can be found in the UF/IFAS EDIS publication, “Key Lime Growing in the Florida Home Landscape” by Jonathan H. Crane: https://edis.ifas.ufl.edu/publication/CH092

UF/IFAS Extension is an Equal Opportunity Institution.