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Vegetable Garden Disease and Pest Controls

Vegetable Garden Disease and Pest Controls

During this growing season monitor your plants and keep them healthy as a healthy plant will be able to better survive an invader attack.

Nematode populations can be reduced temporarily by soil solarization. It is a technique that uses the sun’s heat to kill the soil-borne pests. Adding organic matter to the soil will help reduce nematode populations as well. Nematodes are microscopic worms that attack vegetable roots and reduce growth and yield. The organic matter will also improve water holding capacity and increase nutrient content.

Tomato Spotted Wilt Virus
Credits: UF/IFAS

If you choose to use pesticides, please follow pesticide label directions carefully. Learn to properly identify garden pests and use chemicals only when a serious pest problem exists. If you have questions please call your UF/IFAS county extension office. We can provide helpful information about insect identification.

Organic gardeners can use certain products like BT(Dipel) to control pests. Please remember not every off-the-shelf pesticide can be used on every crop. So be sure the vegetable you want to treat is on the label before purchasing the product.

Follow label directions for measuring, mixing and pay attention to any pre-harvest interval warning. That is the time that must elapse between application of the pesticide and harvest. For example, broccoli sprayed with carbaryl (Sevin) should not be harvested for two weeks.

Spray the plant thoroughly, covering both the upper and lower leaf surfaces. Do not apply pesticides on windy days. Follow all safety precautions on the label, keep others and pets out of the area until sprays have dried. Apply insecticides late in the afternoon or in the early evening when bees and other pollinators are less active. Products like malathion, carbaryl and pyrethroids are especially harmful to bees.

To reduce spray burn, make sure the plants are not under moisture stress. Water if necessary and let leaves dry before spraying. Avoid using soaps and oils when the weather is very hot, because this can cause leaf burn.

Control slugs with products containing iron phosphate.

Cucumber Mosaic Virus
Credits: UF/IFAS

Many common diseases can be controlled with sprays like chlorothalonil, maneb, or mancozeb fungicide. Powdery mildews can be controlled with triadimefon, myclobutanil, sulfur, or horticultural oils. Rust can be controlled with sulfur, propiconazole, ortebuconazole. Sprays are generally more effective than dusts.

 

Beneficial Bugs

Beneficial Bugs

Lady bird beetle and aphids.  Photo:  Julie McConnell, UF/IFAS

Lady bird beetle and aphids. Photo: Julie McConnell, UF/IFAS

 

The most numerous animals on the planet are insects and although less than 1% cause damage to our landscapes, most are viewed as pests.  Many insects perform clean up tasks that keep our environment from being littered with carcasses and trash while others actually attack and feed upon insects that are direct pests to plants.

It is important to recognize that all insects are not pests and take the time to get to know a few that might actually be performing a beneficial job in your landscape.   Probably the most easily recognized beneficial bug family in Florida landscapes are the ladybird beetles (Coccinellidae).  There are several species of ladybird beetles with different food preferences including mildews, mites, whiteflies, scale insects, and aphids.

Another group of insects that include some predatory species is the stink bugs.  Some stink bugs do eat plants, but there are also many that are beneficial such as Florida predatory stink bug (Euthyrhynchus floridanus).  The Florida predatory stink bug preys on velvetbean caterpillar, okra caterpillar, alfalfa weevil, and flatid planthopper.  One of the distinguishable characteristics between plant feeding and insect feeding stinkbugs are the shape of their shoulders.  Plant feeders have rounded shoulders and predatory have points on their shoulders.

The next time you are disturbed by a bug in your garden, take a moment to watch what it is eating and try to identify it before assuming it is a pest.  After all, there are many beneficial bugs that help to balance out the “bad bugs.”

Alert: Ambrosia Beetles !

Alert: Ambrosia Beetles !

Frass (toothpick-like projections) extends from entry holes on a Jeruselum thorn damaged by cold temperatures.  Photo by Beth Bolles, UF IFAS Escambia Extension

Frass (toothpick-like projections) extends from entry holes on a Jeruselum thorn damaged by cold temperatures. Photo by Beth Bolles, UF IFAS Escambia Extension

Winter injury and stress to many trees has attracted granulate ambrosia beetles to landscapes. These beetles mostly prefer weakened trees and cut stumps/logs but have been found to attack some healthy trees as well.

Adult beetles are very small, only about 1/16 inch long and bore into branches and trunks of many woody plants. They will push out small ‘strings’ of boring dust which look like toothpicks. These strings successfully protect the beetles as they establish galleries for laying eggs and rearing young within the tree. The adult females will introduce a fungus (ambrosia) into these galleries on which both the young beetles and adults feed.

 

Ambrosia Beetle Entry Point. Photo by Matthew Orwat

Ambrosia Beetle Entry Point. Photo by Matthew Orwat

Many beetles will bore into a plant, mostly along the trunks. Plants may be ultimately killed, not by the beetles but by the fungi that interfere with the movement of fluids within the tree.

If you notice a tree infested with ambrosia beetles, it is best to remove the plant quickly. Remove all infested plant parts from your landscape. If you have a special plant that you want to save, you may be able to cut it back close to the ground, and allow it to resprout. It would be necessary to monitor the remaining portion carefully for reinfestation and treat with an approved insecticide to prevent beetle entry.

Interior of damaged stem.

Interior of damaged stem.

Bat protection increased during spring and summer

As spring commences and young wildlife of all species are born, everyone’s favorite flying, furry mammal also begins roosting season. Ideally, bats will find shelter in trees, caves, abandoned buildings, and bat houses, but sometimes they end up in a home.  I receive calls often about how to best remove or exclude a group of bats living in an attic or garage. While there are countless benefits (most notably, efficient insect control) to having bats in one’s landscape or neighborhood, most people prefer they not share their own home with them. However, due to their slow reproductive cycle and declining populations in the United States, it is illegal in Florida to prevent bats from returning to any roosting location from April 16 to August 14.  Female bats typically give birth during maternity season to one pup (or rarely, two), which will cling to the mother’s fur to nurse for their first few weeks and months of life. Being nocturnal, this means mothers and babies will be inside a dwelling during the day.  Typically, if a homeowner is trying to exclude bats from a home, they will put up netting or seal up a hole in an attic entry in the evening after bats have flown off to feed on insects at night. However, if this is done during roosting season, young bats left back in the roost while mothers are hunting can get trapped inside a building and will not survive.

A rare set of twin Seminole bat pups with their mother. Photo credit: Carrie Stevenson

A rare set of twin Seminole bat pups with their mother. Photo credit: Carrie Stevenson

This obviously has the potential to cause conflict between homeowners and the bat population. The Florida Fish & Wildlife Conservation Commission has regulatory oversight for bat-related issues, and they will work with citizens to arrange a positive outcome for both the property owner and the animals involved.

Bat populations are declining in North America due to a devastating disease called white-nose syndrome and loss of habitat.  However, you can help these fascinating animals by installing a bat house in your yard.  Keep in mind that bats attracted to bat houses prefer to be in open areas away from trees (where their predators hide), and the house should be installed at least 12 feet in the air.  Bat houses can be purchased or built rather simply—keep an eye out for Extension workshops near you, or visit this UF Wildlife Ecology publication or Bat Conservation International’s website for simple instructions.

To learn more about bats and how to help them, visit this website or contact me or your local County Extension office!

STOP BAGWORMS BEFORE THEY HATCH

STOP BAGWORMS BEFORE THEY HATCH

Bagworms on a stop sign

Bagworms on a stop sign

Northwest Florida is the most southern range of the common bagworm, Thyridoptgeryx ephemeraeformis, but the majority of the plants they feed on can be found here.  Common host trees include Red Cedar, Live Oak, Maple, Elm and Pine.  Other susceptible shrubs include Indian Hawthorn, Juniper, Arborvitae, Ligustrum and Viburnum.

Bagworms overwinter as a clutch of 500-1000 eggs wrapped in the leaves of the infested plant.  In late spring the larvae hatch as tiny caterpillars that disperse to surrounding plants by spinning a silken thread and “ballooning” on the wind.

 

Once established on a host plant the young bagworms begin feeding and constructing a bag which is formed using pieces of twigs, leaves and silk.  

bagworm2

From then on, only the head and thorax of the female bagworms emerge from the foliage bag.  She continually feeds on the plant, leaving it severely defoliated.  As few as four bagworm larvae can cause a four-foot Arborvitae to be so damaged that it can’t ever grow enough foliage to return to a normal appearance.  For four to sixteen weeks the caterpillars feed steadily.  Once the larva has consumed enough food during the last instar, it attaches its bag securely with a thick silken strand to its host plant or nearby structure.  The bagworm seals the posterior end of the bag, molts, and begins pupation.  The bagworm’s 7-10 day long metamorphosis results in a moth.  However, the adult female’s wings and appendages are reduced to mouthparts, legs and small eyes.  She remains in a caterpillar-like state for a couple of weeks.  She releases a pheromone that attracts the male.  The male bagworm emerges as a free-flying, lacey, black moth that only lives one or two days; just enough time to mate with the female in her bag.  Once mated the female then dies, mummifying around her eggs.

 

Bagworm populations can reappear in the same areas year after year.  To control bagworms, mechanical methods and biological insecticides are the most effective practices.  Hand-picking them from late fall to early spring and placing them in a bucket of soapy water or a sealed bag prevents new larvae from dispersing.  Applying Bt, Bacillus thuringiensis, to the foliage is also an effective means of control when applied to new spring growth.  This bacteria stops the feeding of all caterpillars, so be cautious about where it is used. Many desirable butterfly larvae can be harmed if the product lands on other larval plants.

 

 

 

 

 

 

Rethinking the Eastern Mole

Rethinking the Eastern Mole

How can an animal that does such much to help rid your lawn of pests be so hated by most homeowners?  Such is the life of the mole.

The beneficial mammal is a soil dweller that tunnels through the soil, increasing aeration as it searches out a meal of  beetle grubs, mole crickets, and slugs.  Moles prefer loose soil and can tunnel more than 15 feet an hour.  Moist soil brings the food source closer to the surface which in turn bring moles up to expose raised tunnels to homeowners.  These tunnels are mostly cosmetic and show up easily in mulched areas and lawns with heavier weed populations.  Most homeowners with a healthy, thicker lawn will rarely notice mole activity unless they encounter loose areas as they walk over the turf.  These can easily be pressed back down with your foot.

Mole tunnel in weedy area.  Photo:  Beth Bolles, UF IFAS Extension Escambia County

Mole tunnel in weedy area. Photo: Beth Bolles, UF IFAS Extension Escambia County

There are management techniques for moles which include traps and ridding the lawn of the food source.  The best practices are to manage the turf through proper mowing, watering, and fertilizing to create a uniform, healthy cover.  For the most part, mole management is not even required.  Consider the benefits of the moles as predators and allow them to be a natural part of the landscape environment.  For more information on moles read the University of Florida IFAS Extension publication.