Peppers and tomatoes are in the same plant family – solanaceae or more commonly known as the nightshade family – and can be susceptible to some of the same diseases. This is true of Tomato Spotted Wilt Virus (TSWV). The solanaceae family includes potatoes, eggplant, tobacco, petunia, tomatillo and deadly nightshade in addition to pepper and tomato.
Pepper with TSWV. Photo credit: Mary Derrick, UF IFAS Extension.
This virus is spread by very small insects known as thrips. They acquire the virus as larvae when feeding on an infected plant and then transmit the disease when they fly to other susceptible plants as adults.
Initial symptoms are yellowing and distortion of the leaves. The leaves can also display yellow or brown circular ring spots. The severity of the virus can depend on the particular cultivar of pepper, its age and the environmental conditions in which the pepper is growing. Fruit can develop yellow, brown or ring spots as well.
TSWV infection showing ring spot on leaves and lesions on fruit. Photo credit: Mary Derrick, UF IFAS Extension.
If you think your pepper has TSWV, consult your local extension agent to confirm the diagnosis. But once infected, there is no treatment for the plants and they should be pulled up and disposed of in the trash to prevent other susceptible plants from becoming infected.
Homeowners and businesses will often send in plant and insect pictures to the Extension Office. This is a convenient practice for both clientele and Extension Agents, but sometimes it may make diagnosis more difficult and more time-consuming. More often though, a fresh or living specimen is necessary for proper identification.
In an age when high quality pictures can be taken and viewed within milliseconds, plant, disease and insect ID can still take time. Often it is due to the fact we simply don’t know the answer right away and research is required. Sometimes poor picture quality and scale can make the diagnostic process more difficult. To improve identification turnaround time follow these basic steps:
When it comes to taking pictures for diagnostic purposes, more is better. The more pictures depicting angles and magnifications received for a sample the better. If you want a plant identified, take a picture of the entire plant including flowers, leaves, and roots. Take pictures of various stages of spots on leaves, stems, and fruits if you suspect a disease or nutritional disorder. Take pictures from multiple angles and of various body parts for insect identification.
Place an item in the frame of the picture to give a good idea of the size of the specimen through the concept of scale. You could use a ruler, a coin, or even a ballpoint pen. Objects such as coins work well for tiny insects when the measurements on a ruler may be too hard to see in the photo. You can even place the insect on the coin.
A computer keyboard used to show scale for a photo of an aphid. Photo Credit: Julie McConnell – UF/IFAS Extension Bay County
Pay attention to focus on the subject. This is especially true when taking closeup photos and photos of small things with a cell phone camera. Cell phone cameras tend to focus on the background instead of the foreground. Sometimes the quickest solution is to place your hand behind the subject to change the automatic focus and then either leave it in the picture for scale or remove it and snap the picture quickly. It is also important to have a contrasting background such as placing a white or black paper or plastic card behind the subject.
A poor picture of carpetweed growing in a peanut crop.
A good picture of carpetweed using a hand for focus and perspective.
Although it is quicker and easier to email or text plant and insect pictures, the most accurate identification can be accomplished with a fresh sample. Whether you are bringing a sample into your local Extension Office or one of the diagnostic clinics located throughout the state, it is important to follow the guidelines detailed in this publication http://edis.ifas.ufl.edu/sr007.
Extra Credit – If you want to improve you ability to take magnified photos, you may want to build the device featured in the following video “Turn Your Smartphone Into a Digital Microscope”.
When you don’t know what’s ailing your plant, ask an expert.
Many gardeners get stumped when a favorite plant of theirs comes down with a strange “something”. Many of these gardeners know about UF/IFAS Extension and call their local horticulture and agriculture agents for assistance in figuring out what’s going on. However, even these experts are often stumped by what they see. Fortunately, the agents have another layer of experts to fall back on. In addition to the resources in Gainesville, we have the Plant Disease Diagnostic Clinic, located at the North Florida Research Center in Quincy. Plant pathologists here can help determine what fungus, bacteria, virus, or viroid may be the problem.
Plant pathologists are basically plant doctors. They use all sorts of sophisticated techniques to determine what is the cause of a particular plant problem, from growing out fungal spores to examining DNA. Not only do these plant doctors tell us what the ailment is, they also provide recommended cures, or control options. They are also doing research to prevent different diseases from taking hold in our area and reduce the impact on our local growers.
Plant pathologist at work!
At a recent workshop in Quincy, we learned that plant pathology researchers are working on a fungus that affects watermelons, virus and bacteria that can wipe out a farmer’s tomato crop, and a virus that could impact our local roses. Working as a team of scientists, they study these pathogens in the lab and conduct controlled field experiments to figure out which techniques are most effective. Some of this research is leading to different methods and/or products that can help growers and gardeners alike keep their fields and landscapes healthy.
So, if your plants have problems, please contact your local Extension Office. If they don’t know the answer, then the network of scientists, including plant pathologists, in the UF/IFAS Extension family can be called on for backup to provide you with the best possible answer.
Gardeners in Northwest Florida were blessed this spring with conditions conducive to great gardening, mild weather and plenty of rain. However, with those pleasant conditions has come an unusually high occurrence of Fireblight. Cases of Fireblight have been brought into our office almost daily this spring/early summer!
Mature ‘Bradford’ Pear infected with Fireblight
Fireblight is a difficult to control, rapidly-spreading disease caused by a bacterium (Erwinia amylovora) that affects many fruit trees, especially apple and pear but is also seen on quince, crabapple, hawthorn, loquat and photinia. Fireblight is generally noticed in late winter and early spring during periods of frequent rainfall as the plant begins to bloom and leaf out. The bacterium enters the plant through the opening flowers causing them to blacken and die. The disease then makes its way down the infected stem, destroying newly developing twigs along the way. Most homeowners notice the problem at this point in the progression; the new shoots have died, turned black and hold on the plant, giving it the tell-tale “burned” look. Homeowners also generally notice sunken lesions, or cankers, that form on the infected stems.
So, with a problem as unpredictable and destructive as Fireblight, what can one do to prevent it or combat its spread? There is no one method that can prevent or cure a Fireblight infection but there are several precautions homeowners can make to mitigate its effects.
Plant resistant species and/or resistant cultivars of susceptible species, such as pear and apple. Under conditions like we’ve had this year, no pear or apple is immune but these cultivars have some proven resistance:
Edible Pear: ‘Keiffer’, ‘Moonglow’, ‘Orient’
Apple: ‘Anna’, ‘Dorsett Golden’
Ornamental Pear: ‘Bradford’, ‘Cleveland Select’
Remove infected and dead wood when the tree is dormant. Make a clean cut at least 12” below the last sign of infected wood and dispose of it. It is always a good practice to sanitize your pruners between cuts on a diseased tree. Also, there is little evidence to suggest that pruning out diseased wood on actively growing plants has much effect on further disease spread as long as conditions are still suitable for Fireblight formation.
If you have noticed Fireblight on your trees in the previous year, it is good practice to make a preventative spray of a copper fungicide prior to the plant breaking dormancy.
During bloom, streptomycin may be applied every three or four days for the duration of the bloom cycle to prevent infection. Consult the label for required days between spraying and consumption.
Fireblight is bad news in a fruit orchard but homeowners can take heart in the fact that the condition is not always fatal, especially if the preventative measures outlined above (proper cultural practices, proper pesticide use, and planting of resistant cultivars) are taken!
Do you have azaleas or camellias with leaves that are thickened, curled and waxy in appearance? This is fairly common this year and is caused by a fungus.
Camellia leaf gall on Sasanqua Camellia. Note swollen, malformed leaves. Photo credit: Larry Williams
Exobasidium vaccinii is a fungus that causes leaves, and in some cases flower petals, to enlarge abnormally and is commonly referred to as azalea leaf and flower gall.
Infected azalea and camellia leaves become large and distorted. Eventually a white powder covers the galls. The white growth consists of spores, which is how the fungus reproduces. Galls ultimately turn brown and harden. Not every leaf will be infected.
The disease relies on airborne spores produced in the whitish mold on the surface of galls in late spring to early summer to reproduce. Some plant pathologists believe that once the spores are released, they are blown and washed to leaf and flower buds where they cause new infections. Galls then form the following spring. Other plant pathologists think that the spores are produced the following year from the old dried, brown galls that fell to the ground around infected plants the previous year. In spring, the spores blow and splash onto new leaves and petals as they emerge causing infection. One or both lines of thought may be true. But in either case, it’s important to remove and dispose of infected leaves before they turn white with spores.
Once you see evidence of infected leaves, it’s too late for chemical control. Besides, there currently is no effective or practical fungicide to control this disease in home landscapes. But you can reduce the amount of infection the following year by pruning infected leaves and throwing them away before spores develop. After removing infected leaves with galls, never leave them on the ground around the plants.
It’s best to bury, burn or place infected leaves in a plastic bag and throw them away. This disease is more severe during a cool, wet spring, which we experienced this year. It’s advisable to not add to the problem by artificially providing the “wet weather” the spores need by frequently using an overhead sprinkler and keeping the foliage wet in the spring during disease development. This is exactly what this and many other plant diseases need – wet conditions. It’s best to water established landscape plants on an as needed basis.
In the home landscape, the fungus does not cause any long-term problems for the plant. It just makes the plant’s leaves look ugly. Infected leaves will usually fall prematurely.
The panhandle of Florida is a great place to grow citrus with our plentiful sunshine and sandy soil. But some varieties do better than others. Here are some that thrive in the more northerly climes of Florida:
Nagami kumquat. Photo credit: UF/IFAS.
Satsuma mandarin is cold hardy to 15°F once established. There are a few different available cultivars with fruit ripening October through December. Fruit needs to be picked promptly when ripe.
Kumquat is cold hardy to 10°F once established. ‘Nagami’ and ‘Meiwa’ are the two common cultivars of the small tart fruits. Fruit matures in fall and winter and holds fairly well on the trees.
Calamondin is a lesser known variety that bears small fruit that resemble tangerines. The tart fruit is great for jams and chutneys. Fruit is borne all year.
Some of the sweet oranges that do well in the panhandle are Navel, Hamlin and Parson Brown. They are cold hardy to 14°F once established and are harvested November through January.
Minneola or Honeybell tangelo is also hardy to 14°F and harvested in January. This is a cross between a Duncan grapefruit and a Darcy tangerine. This bell-shaped fruit is very juicy and sweet. Unlike the other citrus varieties, it needs another citrus nearby for cross-pollination in order to produce an abundant crop.
Meyer Lemon is the choice to make if you would like to grow lemons in the panhandle. Other lemons may be damaged by our occasional freezes.
Grapefruit and lime can be grown – although unreliably – on the coast with protection from northwestern winter winds. They are much more susceptible to freezes in more northerly panhandle locations.
Citrus canker symptoms on leaves, fruit and stem. Photo by Timothy Schubert, FDACS
There are threats to our dooryard and commercial citrus from pests and disease. Only vigilance will help to combat the challenges so that we may continue to grow and enjoy our citrus. What can we do to protect our citrus?
Report any serious diseases like suspected citrus canker or citrus greening to the Division of Plant Industry by calling toll-free 1-888-397-1517. Inspections and diagnosis are free. Citrus canker has been confirmed in south Santa Rosa County in the past 3 years.
Purchase citrus trees only from registered nurseries – they may cost a little more but they have gone through an extensive process to remain disease and pest free. That will save you $$ in the long run!
Don’t bring plants or fruit back into Florida – they may be harboring a pest!
Citrus trees or fruit cannot move in or out of the State of Florida without a permit. This applies to homeowners as well as to the industry. This rule protects our vital dooryard trees and citrus industry.
