Fall Vegetable Gardening Workshop August 6
What’s Wrong with My Plant…Picture
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”.
Purple Triangles in the Trees
From time to time I am reminded of how little I know. Honestly, I am reminded on a daily basis. A few weeks ago someone asked me about the purple things hanging from the trees. Luckily, the person gave me some good southern directions on where I could find one of these things hanging around in Marianna. So I drove out to the site to get a better look. What I saw hanging in the tree was a three-sided, purple triangle about two feet tall and a foot wide. It looked to me like someone got a box kite stuck in a tree. Upon further research, it was determined this box kite like thing was a monitoring trap for the emerald ash borer (EAB).
A woman hanging an emerald ash borer trap in a tree. Photo Credit: Texas A&M University
The emerald ash borer (EAB) is a destructive, exotic wood-boring beetle native to Asia. It was first discovered in North America in July 2002 and has made a home in Michigan, Ohio and Ontario, Canada. Millions of ash trees have been killed by the EAB in Michigan and invested ash tree nursery stock in other states indicates the potential for increased spread of the pest. EAB has made its way to the south and has been found in Louisiana and Arkansas.
Monitoring traps are not the only means of EAB detection. A proactive approach utilizing observant citizens can help keep an eye out for potential populations. You can use these tips to monitor your community for emerald ash borers:
Ash Tree Identification – Ash trees are identified by their (1) opposite branching pattern, (2) compound leaves with 5-9 leaflets, and (3) diamond shaped bark ridges on mature trees.
A compound leaf of an ash tree. Photo Credit: FDACS
Woodpecker Damage – Of course, not all woodpecker damage on ash trees is associated with EAB infestation, but woodpecker damage in the upper part of the tree can indicate their presence. The woodpecker damage is usually accompanied by vertical cracks in the bark.
Canopy Thinning – As the attack progresses, bark cracking continues and the canopy in the upper half of the tree begins to thin.
Michigan ash tree showing decline due to Emerald ash borer. Photo Credit: USDA
Tunnels and Holes – The emerald ash borer makes distinctive S-shaped tunnels that differ from damage from other borers.
EAB Damage (left) VS Other Borer Damage (right). Photo Credit: Texas A&M University
This beetle hitchhikes on firewood and infests new areas at an alarming rate. Although the EAB has not yet been detected in Florida, transporting firewood from other states puts Florida ash trees at risk. Your help is needed to detect possible infestations so they can be quickly eradicated. The information available at the following links will help you identify the EAB, EAB host trees, and infestation symptoms.
Tipping the Scales
Scales on a Chinese Elm.
Scales on a Chinese Elm.
Last week as I was basking in the shade of the Chinese Elms (Ulmus parvifolia) in my yard, I noticed some strange lumps on the twigs. Upon further investigation, I realized the “lumps” were scales. Scale insects are serious pests of a number of ornamental plants. Here in Florida there are 13 different families of scales with the most common being armored scales, soft scales, and mealybugs. Scales have piercing-sucking mouthparts which they use to siphon fluids from the leaves, stems, and sometimes roots of many ornamental plants. Heavy infestations cause extensive leaf yellowing, premature leaf drop, branch dieback, and eventually plant death.
Scale Biology
The life cycle of a scale begins with eggs being laid beneath wax coverings or beneath the adult female. Eggs typically hatch in 1 to 3 weeks. The newly hatched nymphs, called crawlers, move around a plant until they find a spot to feed. Once a feeding site is located, their piercing sucking mouthparts are inserted into the plant and the crawlers begin to feed and grow. The males of many scale species develop wings as adults and fly to other plants to reproduce.
The magnolia white scale. Credits: University of Florida
Armored Scales
Armored scales get their armor by secreting a waxy covering over their bodies that is not attached. The scale lives under this covering and uses it as a protection to feed under. Armored scales can be almost any color or shape and range anywhere from 1/16 to 1/8 inch in diameter. For females, these shapes range from circular to oval to long and slender. The males typically have coverings that are more elongate and smaller than the females. As adults, the males are tiny, winged, gnat-like insects and are rarely seen.
Hemispherical scale on coontie. Credits: Lyle Buss, University of Florida
Soft Scales
Similar to armored scales, soft scales secrete a waxy covering, but it is attached to their bodies. Soft scales can be a number of colors, shapes, and sizes and range anywhere from 1/8 to 1/2 inch in diameter. Their shapes vary from spherical to nearly flat.
Mealybugs. Credits: James Castner, University of Florida
Mealybugs
Mealybugs are soft-bodied insects that possess a covering of flocculent, white, waxy filaments. They are about 1/8 inch in length and usually pinkish or yellowish in color. Mealybugs have piercing-sucking mouthparts which they use to siphon fluids from the leaves, stems, and sometimes roots of many ornamental plants. Mealybug damage produces discolored, wilted, and deformed leaves.
Scale and Mealybug Management
- Cultural Control – Plant inspection prior to purchase or installation is the first line of defense against a scale or mealybug population. Make sure to inspect the undersides of leaves and plant stems. Infested sections of plants can be pruned and plant material should be cleaned from the planting area and discarded. Also, you can increase air flow and decrease humidity by proper installation and pruning. Over-fertilizing can also increase pest populations.
Larva of a brown lacewing. Credits: Lyle Buss, University of Florida.
- Biological Control – Predators, such as ladybugs and green lacewings, are usually present in large enough numbers to suppress scales and mealybugs to a desirable threshold. However, broad-spectrum insecticides and bad weather can reduce predator numbers. Look for signs of predation by inspecting dead scales for jagged holes in their waxy coatings. If predation signs are present, use more selective chemical controls and oils as opposed to broad-spectrum products.
- Chemical Control – Timing is everything when it comes to managing scale and mealybug insects. Crawler activity is more pronounced with the flush of new plant growth in the spring. Before application, prune infested plant parts off first to promote greater penetration of insecticides into the foliage. Contact products (acephate, bifenthrin, carbaryl, etc.) must be applied to inhibit the crawler stages of these insects and systemic products (acetamiprid, imidacloprid, thiamethoxam, etc.) can be used on the sessile growth stage. Plants should be sprayed thoroughly to the point of drip or “run off” from leaves, twigs, and stems. Repeated applications may still be necessary even if the timing is right, as crawler populations are often large and crawlers like to hide under old waxy scales. Systemic drenches are also a viable option. With good spray coverage, horticultural oils can kill scales at all stages of growth. Refer to the product label for phytotoxicity and temperature guidelines. Even after successful treatment, the outer coatings of the scales may remain on the plant material for weeks, which can be unsightly. The best way to determine if scales are dead is to squeeze them. They will be dry when squeezed if they are dead and they will ooze liquids if they are living (they were at least alive to the point of being squashed).
For insect identification and additional information on scale control, please see:
A Guide to Scale Insect Identification
Evergreen Wisteria – An Excellent Alternative for Chinese Wisteria
Are you looking for a way to jazz up a fence, trellis, or arbor? Are you looking for year-round color in your garden? Are you looking for wonderful, fragrant blooms in the summer? Than evergreen wisteria (Millettia reticulata) may be the right plant for your place!
Evergreen wisteria growing on a fence. Photo: University of Florida/IFAS
Evergreen wisteria is not only a beautiful vine, but it is an excellent alternative to that pesky, invasive Chinese wisteria. Sometimes referred to as summer wisteria, this plant is native to China and Taiwan. As you may have noticed by its scientific name, Millettia reticulata, is not a true wisteria but it is in the same plant family, Legumaceae or the bean family.
Evergreen wisteria in bloom. Credit: University of Florida/IFAS
Evergreen wisteria is a woody vine that has glossy, thick green leaves and clusters of small, fragrant, purple flowers. The plant can reach a height of up to 30 feet, but can easily be controlled with pruning. It blooms in the summer, and often into the fall, with deep purple, pea shaped blooms. Although its common name states it is evergreen, it is often semi-evergreen in the Panhandle. Evergreen wisteria grows best in full sun, but can tolerate partial shade.
Evergreen wisteria can tolerate a wide range of soil pH as long as the soil is well-drained. It is a twining vine and may need a little help to start growing on a structure. It can be left alone to climb tall structures like pergolas and arbors, but you may want to selectively prune the plant to encourage it to leaf out at its base when training on a trellis or fence. Deadheading (removing spent blooms) will encourage an elongated bloom season.
Evergreen wisteria can help add an additional visual dimension to your landscape and it won’t invade your space like its distant cousin.