Hydrangea leaf spot disease Photo credit: Larry Williams
It is not uncommon to see leaf spots on your hydrangeas during late summer and fall.
These spots are caused by a number of fungal diseases. Plant fungi and wet weather go hand-in-hand. Florida’s high humidity, heavy dews and frequent rains during spring and summer provide perfect conditions to allow fungal diseases to flourish. Bacterial leaf spots can be part of this foliage disease mix, too.
Common foliage diseases seen on hydrangeas this time of year include Phyllosticta leaf spot, Target leaf spot, Bacterial leaf spot, Botrytis and Cercospora leaf spot.
These foliage diseases are the norm rather than the exception as we move into the wet summer months and on into fall. As a matter of fact, you would be hard-pressed to find any hydrangea in our area without some evidence of infection now.
This late in the year it is more of a “grin and bear it” problem. In other words, it’s too late to do much about the fact that your hydrangea plant has leaves covered in ugly spots. By now many of the infected leaves are turning brown, withering and dropping prematurely from the plant.
Cercospora leaf spot is one of the most common foliage diseases of hydrangeas. Along with most of the leaf spot diseases, it begins as small dark-colored specks on the leaves. The small specks generally go unnoticed. But as the spots continue to slowly enlarge, mostly maintaining a circular shape, they become more obvious. With heavy infection, individual spots can coalesce forming larger irregular shaped brown areas on individual leaves. The individual spots may have a purplish halo with gray center.
There are some fungicides that can help prevent these leaf spots. But you’d have to begin treatment early in spring before any leaf spots exist and spray the plant every 10 to 14 days during favorable disease development (humid, rainy weather), which is pretty much our spring and summer months. These types of diseases are prevented, not cured. That’s the “grin and bear it” part of waiting until now.
The fungus survives on infected leaves. So, the best thing to do now is to remove and dispose of infected leaves. Also, be careful to not wet the leaves when irrigating the plants during the growing season.
New leaves of spring should be spot/disease free as they emerge. But the cycle of life for these leaf spot diseases will again result in spotted/diseased leaves on your hydrangeas next summer and fall without persistent treatment.
The good news is that these leaf spot diseases normally do not cause permanent/long-term damage for hydrangeas. They just make the plant look ugly.
On June 6th, we held an Invasive Species Workshop: Air Potato Challenge and Species Awareness day at the UF/IFAS Extension Office in Panama City. Over 700 air potato leaf beetles were distributed to more than 30 sites in Northwest Florida by citizen scientists to help manage the invasive air potato vine!
Rick O’Connor, UF/IFAS Extension, tells us about the ball python, a potential invasive species. Rick also provides an overview of keeping pythons and other snakes as pets. http://edis.ifas.ufl.edu/pdffiles/UW/UW34100.pdf
Holli Nichols, FWC, tells us about the Wildlife Assistance program for homeowners and property owners. Holli helps out find solutions for negative encounters with Wildlife. Most problems are easily solved and she provides a few tips. Holli also tells us about the FWC Pet Amnesty Program for Exotic Pets. Watch to learn more. http://myfwc.com/conse…/you-conserve/assistnuisance-wildlife
Kira Burdeshaw, SCN of NW FL, shows off the tokay gecko we found at the Extension office on the front porch earlier in May. The Gecko moved in with Kira and her other reptiles at the Science and Discovery Center.
…http://myfwc.com/wildlifeha…/nonnatives/reptiles/tokay-gecko
Derek Fussell with FWC Invasive Aquatic Plant Management talks about Giant Salvinia, a species of concern for Deer Point Lake in Bay County, Florida. Here’s a link to a story about the discovery of giant salvinia in Bay County from 2016 https://nwdistrict.ifas.ufl.edu/…/nisaw-2016-working…
Derek Fussell shares a behind the scene’s view of their new boat for controling aquatic plants in Bay County and Northwest Florida. We will visit with Derek and Jamie later and show some of the aquatic invasives they work to control everyday!
Over the last month or so, home gardeners and commercial growers alike have noticed what look to be large dust particles floating through the air. It’s probably not uncommon to have inhaled a few or even a few hundred of these mysterious particles. Most likely, these “particles” aren’t dust at all but whiteflies instead. Whiteflies are small (less than a tenth of an inch long), white, soft-bodied insects. They aren’t flies but are considered ‘true bugs’ by entomologists. The most common whitefly species in Northwest Florida is the silverleaf whitefly, also known as the sweetpotato whitefly. Whitefly numbers have exploded exponentially this year because of last years’ mild winter. These irksome insects feed on a variety of annuals, shrubs, vegetables and trees.
Magnified whitefly adults and eggs. Photo Credit: James Castner, University of Florida/IFAS.
Whiteflies typically feed on the underside of leaves. Initially, disturbed leaves will become pale in color, then a sticky substance may develop on the surface of the leaves. This sticky substance is called honeydew. Honeydew is actually a sugary substance excreted by the whiteflies as part of their elimination process, similar to what aphids and scale insects produce. After honeydew is deposited, sooty mold develops to feed on this readily available sugar source. Sooty mold is a fungus that forms a gray to black colored coating on plant leaves. It normally grows on leaves that were previously covered with honeydew. Sooty mold hinders the ability of leaves to absorb light and ultimately limits photosynthesis.
Pale squash leaves due to feeding from whiteflies. Photo Credit: University of Florida/IFAS.
So what should be done to control whiteflies? It depends on what is being grown. If whiteflies are present, the role of beneficial insects should be taken into consideration. Plenty of predatory insects such as lady bugs and green lacewings are around to feed on whiteflies. In fact, leaving the whiteflies alone on your trees and shrubs will attract more predatory insects. Below are some whitefly control methods that produce minimal damage to beneficial insect populations.
Whitefly Control in Vegetables
Sticky Traps – Yellow sticky traps are a good way to monitor whitefly populations and can help determine when insecticide application is appropriate.
Insecticidal Soaps – Insecticidal soaps are usually applied as a 1 to 2 percent solution (2½ to 5 tablespoons per gallon of water). It is important to follow the application directions on the label. Insecticidal soap should be applied in the evening, when the sun is low in the sky and the temperature is below 85°F. Some insecticidal soaps available at local lawn and garden centers include: Bonide Insecticidal Soap, Bonide Insecticidal Soap, and Bayer Advanced Natria Insecticidal Soap.
Horticultural Oils – Horticultural oils should be handled like insecticidal soaps. Like the soaps, they should be applied in the evening. Some horticultural oils available at local lawn and garden centers include: Bonide All Seasons Spray Oil, Southern Ag Parafine Oil, and Garden Safe Neem Oil.
Other Insecticides – Harsher chemicals are not recommended for the home gardener, because whiteflies have become resistant to most products on the market. Use of broad spectrum insecticides may also contribute to an increase in whitefly populations because they kill beneficial predatory insects.
Hopefully winter will be cooler this year and the profuse whitefly population will be knocked back. Until then, we wish all home gardeners the best of luck with fall gardening!
Most of you plant a spring vegetable garden with a number of different vegetable types. However, you may not realize that you are improving the health of your soil and your crops by planting a diverse garden. Intercropping is a gardening practice of growing different crops in the same field. When planting a mixture of crops in the same field year after year, it is important to rotate the location of each type of vegetable. This is a practice known as crop rotation. Intercropping and crop rotation will help reduce insect pest populations, increase beneficial insect populations, and reduce weed populations.
Crop Diversity
Growing plants in your garden that pest insects don’t like to eat makes the pests work harder to find what they do like to eat. Studies have found reduced whitefly numbers on squash plantings mixed with a crop of buckwheat when compared to squash planted alone. Another crop mixture that may be unintentional, but may work in your favor is a row of crapemyrtles along the edge of your garden. Crapemyrtles will attract the crapemyrtle aphid which will attract predatory insects. When the predatory insects run out of crapemyrtle aphids to eat, they will move to your garden and begin to hunt pest insects on your vegetable crop.
Squash with living mulch of buckwheat. Photo Credit: Oscar Liburd, UF/IFAS Extension
Trap Cropping
A trap crop is a plant that attracts a pest insect away from your food crops. Trap crops work best when planted at the edge of your garden, along a fence row, or in movable containers. A bare space, let’s say 5 feet or so, should be kept between your trap crop and your garden. This will help keep the pests from moving on to your vegetables. When you find a good population of pests on your trap crop then it is time to spray them with insecticide or cut the crop down and remove the debris to a location far from your garden. If your trap crops are planted in containers, then it makes them that much easier to remove from near the garden area.
Cover Crops and Green Manure
Soil organic matter can be increased by the use of green manure and cover crops. Cover crops are generally planted during the off-season, but they can be planted in between vegetable rows and tilled in at a designated time as a green manure. Both cover crops and green manure improve the production of your garden by:
Suppressing weeds by competing for water, light, and nutrients;
Holding the soil in place and preventing erosion;
Scavenging for nutrients that can be utilized in future crops;
Reducing nematode populations;
Providing a habitat for beneficial insects.
A mixed plot of cover crops and trap crops. Photo Credit: UF/IFAS Extension
A number of different crops can serve as cover crops or green manure crops. Most are legumes (bean family) or grasses. A few that you might like to give a try are:
Mounds of sand made my pocket gopher along roadside. Photo Credit: Larry Williams
Pocket gopher is a furry animal known by many locals as “sandy mounder.” It was given this name because of the sandy mounds of excavated earth that the gopher pushes out of its underground burrows. The name sandy mounder, with time, became “salamander.” This animal is not a salamander at all. Salamanders are slimy amphibians shaped like lizards. Salamanders are often known as “spring lizards” in Florida.
To make this nomenclature problem more confusing, in some areas of Florida gopher means a certain burrowing tortoise – the gopher tortoise.
To simplify things keep in mind that in Florida “spring lizard” can mean “salamander” and “salamander” can mean “gopher” and “gopher” can mean “turtle.”
“Gopher” is a confusing word all over the country. Jeff Jackson, retired wildlife biologist with University of Georgia Extension says, “The Richardson’s ground squirrel of the west is called gopher. So is the thirteen lined ground squirrel of the Great Plains and Midwest. Moles are called gophers in many areas. And voles (certain short-tailed mice) are called gophers in some states.”
Jackson says there are six species of “sure enough, genuine pocket gophers in the United States.” Our pocket gopher is the Southeastern Pocket Gopher, found in north Florida, south Alabama and south Georgia.
The pocket gopher spends its time underground making tunnels and nests, eating roots and bearing and raising young. It may venture into residential areas where it can damage plants by feeding on tree and shrub roots or bulbs and tubers of various plants.
A pocket gopher can make fifty or more sandy mounds in a relatively short period of time. These mounds, which are normally four to six inches high and possibly a foot across, are what get homeowners’ attention. The mounds can “popup” overnight in lines or rows. They resemble fire ant mounds; however, they contain no ants.
The pocket gopher is a rodent that grows to about a foot long, has a short tail and weighs about half a pound. Its name comes from the large fur-lined pouches on the outside of its cheeks.
Even though they do contribute to the formation of soil and provide a food source for some predators, sometimes their damage may justify control measures.
Trapping is the most effective option. No chemical repellents are known to be effective. It’s illegal to use any poison to kill gophers. Vibrating devices have not been proven to repel gophers. A long held belief that Wrigley’s Juicy Fruit gum kills gophers by blocking their digestive system has been proven to be false.
On June 6th, we held an Invasive Species Workshop: Air Potato Challenge and Species Awareness day at the UF/IFAS Extension Office in Panama City. Over 700 air potato leaf beetles were distributed to more than 30 sites in Northwest Florida by citizen scientists to help manage the invasive air potato vine!
