Disease

 

Blossom End Rot

Q:  Last year I had the ends rot out of watermelon and cantaloupe.  They bloom but no fruit developed. This year, I planted zucchini instead and I am getting the same problem. The fruit is rotting out from the bloom end.  I now have cantaloupe in bloom, but no fruit started.  What can I put on the plants to prevent the end rot?

A:  Blossom end rot is a common problem on plants in the melon family. The root cause generally is the lack of calcium in the soil or the ability of the plant toBlossom End Rot on Melon update calcium.  We would suggest you have your soil tested every few years.  The cost is minimal ($7) and the University of Florida will run a complete nutrient analysis for you - money well spent.  Vegetables grow best when the pH of the soil is close to 6.5.  In addition to being sure the soil has enough calcium it is equally important that water be available on a regular basis so the uptake of nutrients to the plant is efficient.  If the plants experience drought at the time when the blossom or fruit is forming then maturity of the fruit or rot can occur.  You can come to the Yulee satellite office or the main office in Callahan to obtain a soil test kit.  Call us for directions 904 - 491-7340 – Yulee or 904 879-1019 – Callahan.

Castor Bean

Q: Could you help me determine the name of the plant that just appeared in my garden one day in late summer?  It had interesting foliage so I let it grow. It may be an invasive weed but it turned out to have a very pretty and unusual flower.  Are there any problems with this plant?  Folks have been asking for seeds from it. 

A:   I sent your photos to the University of Florida Herbarium and below is the response from one of the specialist.  “The plant is Ricinus communis L., commonly known as Castorbean, Castor Oil Plant, or Palma-Christi, in the Euphorbiaceae (Spurge Family). Castor Bean It is thought to be native to Africa but is widely cultivated as an ornamental and as a source of seed oil used in industry and medicine.  It is also widely naturalized.  In Florida it has escaped from cultivation and is frequently found on disturbed sites.  The Florida Exotic Pest Plant Council lists it as a category II invasive for northern, central, and southern Florida.  It can be safely cultivated as an annual in colder climates, but in northern Florida it often sprouts back from the roots after freezing and the seeds are dormant in the winter and sprout once temperatures have warmed.  There are a number of cultivars, some of which are very attractive ornamentals, but because of its aggressive tendencies this plant probably should not be grown in Florida.

All parts (but especially the seeds) are highly toxic if consumed; the toxic principle is called Ricin.  Because of its toxicity the oil must heat treated before it is safe to consume medicinally.

For more information on this plant see the following websites:
http://www.floridata.com/ref/R/rici_com.cfm  (info on cultivation)
http://www.hort.purdue.edu/newcrop/duke_energy/Ricinus_communis.html  (info on uses)
http://www.issg.org/database/species/ecology.asp?fr=1&si=1000&sts=  (info on invasiveness)

Downy Mildew

Q:  The hickory trees in my yard and those around the neighborhood seem to be doing poorly. Some of the tops of the leaves are turning brown and the undersides have white spots. 

A:  I am so glad you brought me some clippings of the tree because it was hard to do a diagnosis over the phone.Downy Mildew  After looking at the leaves under a microscope I was able to identify the culprit as downy mildew, which is a common disease on walnut and hickory.  The white mold occurs on the underside of the leaves in early spring when temperatures are low but moisture is high.  This year we have had an abnormally cool spring which contributed to the large downy mildew outbreak on the hickory trees around your neighborhood.  You can expect the disease to reappear next year if weather conditions are repeated.  Downy mildew will not kill the tree and is really more of a nuisance than a true problem.  During the summer the leaves will shrivel and drop and this would be the best time to clean up the leaf litter.  This simple sanitation method is important in disease control but there is no chemical we would recommend to manage the disease.  This is one of those grin and bare it disease situations.    

Fungus

Q: What are these yellow spots on my shrubs and what can I do to get rid of it? 

A:  Thanks for bringing me a sample of the problem. Angular Leaf Spot I have addressed this before in this column but it bears repeating as you are the third person this week with the same problem. Managing the disease can be done but it will take some effort.  Your shrub is called Pittosporum and there are several varieties of the plant from medium sized trees to small dwarf plants.  Some of the plants are solid green while others some in a white and green variegation. Once established, these plants are extremely drought tolerant and really do not require irrigation unless we go through a drought period, which is true of most woody tree and shrubs. The golden, orange spots on the leaves are caused by a fungus.  It is important for the leaves of the shrub to remain dry – so be sure to keep irrigation sprays away from these plants. Good air circulation is also important, so light, selective pruning can be done to allow for good air flow.  The disease is called angular leaf spot and it is a common problem on Pittosporum plants.  Consider using a fungicide containing the active ingredients of myclobutanil or azoxystrobin on the new growth.  Please follow the directions on the pesticide label – the label is the law.  Do not use a fungicide containing the active ingredient chlorothalonil (Daconil) as it has been known to damage Pittosporum. 

Q: What is wrong with my plant? The plant produces beautiful fruit, but the leaves are spotted.

A: After looking at your leaves I determined the cause was fig rust, which is a fungus. The disease is first evident as small, angular, yellow-green flecks on the leaf. The spots do not become extremely large but do become more yellow and finally a yellowish-brown. The margin of the spot is reddish in color. On the upper surface the spots are smooth, while on the lower surface the spots appear as small blisters. Brown spores are released from the blisters at maturity. As infection continues, the leaves become more yellow, and finally they begin to die around the leaf margins. Eventually death and defoliation occur. Complete defoliation can occur in two or three weeks. Fig rust generally becomes a problem as the fruit reaches maturity. Therefore, fungicide applications should be started in the early spring when the first leaves are completely grown. Make additional applications as new growth is formed. Do not spray when the fruit is one-fourth inch in diameter as the spray residue will make the fruit unattractive. Resume spraying after the fruit has been harvested. As always, follow the directions on the pesticide label.

Q :  I have circular spots on my Indian Hawthorn. What is it?

A: The cause of the spots on the leaves is a fungus called Rhizoctonia solani Kuhn. The leaf spots are tan with alternating light and dark concentric rings. The spores of this fungus are easily spread during warm, rainy weather. Good sanitary conditions are important such as removal of leaf litter and avoid overhead irrigation which increases the chance of spreading the disease. A fungicide will be required to eliminate the disease.

Q:  I have sent you pictures of something I found this morning on our cedar mulch in back of our house.  I have never seen this before and would like to know what it is - Birds Nest Fungiand if we need to try to kill it.  It is in the back of our house on the East side, but gets little sun because of a large oak tree.  It is also to the side of a "Macho fern."  It appears to be perfectly formed little cups with seeds of some sort in it.  These little "cups" are between 1/8" and 1/4" in diameter. Thank you for any information you can give me on this growth.

A:  The photos were wonderful and made the identification very easy.  The small structures are birds nest fungi.  These odd and fascinating little fungi look like tiny birds' nests with small eggs.  Bird’s nest fungi belong to a group called saprophytes that live on decaying material.  They are in fact part of the “full circle of life” – those who eat and those who are eaten.   The fruiting bodies form little cuplike nests which contain spore-filled structures that resemble eggs. The nests are called "peridia" and serve as splash cups; when raindrops strike the nest, the eggs (called "periodoles") are projected into the air, and they latch onto twigs, branches, and leaves waiting for the perfect weather conditions to develop into new birds nest fungi.  They do little harm to the environment so no chemical treatment is necessary.  If you wish to get rid of them, collect them into trash bags and toss them.

Fusiform Rust

Q: My home backs up to a large natural area and I have seen a few of the small pine trees with large areas of an orange colored powder on some of the trunks or stems.  It is such a bright orange color that it reminds me of cheddar cheese.  What is it? 
A:  More than likely, this is a disease called Fusiform rust, caused by the fungusFusiform Rust Cronartium quercuum.  This fungus is native to the southern United States so the disease if very common in our area. Many rusts require an alternative host to complete the life cycle and this one is no exception.  Part of its life cycle is spent on oak trees which is a requirement for survival.  It causes little or no noticeable damage to the oak tree but the second part of its life cycle does cause damage to pines.  The fungal spores are spread by wind from the pine to the oak and back again. Usually during the spring (March or early April) galls will form on pine trees. These galls will produce the bright orange colored spores you spotted which are carried by the wind onto newly forming oak leaves.  These spores will form pointed structures on the underside of the oak leaves where they are transferred by the wind onto pines. There are some management strategies for pine farms but for the average homeowner, it is not practical to remove oak tree stands from around your property.  One option would be to remove the small pine trees if this natural area is part of your private property. Since this gall is part of the trunk of the tree, it is unlikely the tree will survive anyway.  

 

Mold

Q: It looks like someone sprinkled bath salts on my straw flowers.  What could be causing this? 

A:  This condition is the result of all the rain we have been receiving lately. Dog Vomit Slime Mold What you have is a slime mold, Fuligo septica aptly named “dog vomit.”  I hope none of you are eating breakfast or lunch now as this will not make it very appetizing.  We will probably see more of this in the next week with additional rains. It can show up on anything including palms, lawngrass, or mulch. There is not need to apply any chemicals as it would not get rid of it any quicker. As the weather changes and it will because this is Florida, this slime mold will also disappear. If you feel you just cannot stand it, collect as much as you can, bag it and throw it in the trash. However, this could be another opportunity for us to not sweat the small stuff - just grin and bear it. Attached is a photo I took of the slime mold, but a mere photo does not do it justice.  One should experience this slime mold up close and personal. For those of you with children – take advantage of a wonderful teaching moment.  

Q: We noticed an orange looking fungus about 3 inches from the ground and about 5 inches horizontally on one the palms.  Is this a virus? I have attached the pictures.  Do we need to have these palms taken down immediately? Thank you for all of your assistance

A:Thank you for sending me the pictures of your palm tree;Slime Mold it certainly helped identify the culprit. The pathology department from the University of Florida has identified this organism as a slime mold (not a virus) called Fuligo septica, which occurs when the weather is wet.  It goes by a lot of common names such as “yellow mold” or the unpleasant name of “dog vomit mold”. Slime mold grows on all sorts of organic debris, engulfing bacteria and other organic particles on the surface. It is most often found on dead grass clippings on the lawn or mulch around flowers and ornamentals. It will not kill your palms and once dry weather returns, it will erode away. If you have a sprinkler head in this area, be sure to cut it off because a sprinkler head will contribute to the palm's stress.  Palms are generally drought tolerant and do not need additional watering. If this palm is in a flower bed with other plants that require more water, consider removing the needy plants to another area. Partnering plants with similar water and sun requirements makes life easier for you and the plants.  I would also remove the pine mulch several inches away from the trunk of the palm.  Mulch should never touch the trunk of trees, shrubs or palms and the mulch should be no more than 2-3 inches deep.

Q: I have holly bushes all around my house and they are all doing fine except in one area the holly is covered with a black, flaky coating on the leaves and stems. The area where the plants are doing badly is very wet and doesn’t get as much sun as the other parts of the house. What is wrong with these few holly plants?

A: Without realizing it, you have answered your own question. The holly receiving sun and good air circulation are in the correct place and that is why they are doing so well. The black coating you see on the other holly is called sooty mold and is the result of a honeydew excretion from insects. In fact, after examining a few stems I found 3 different kinds of scale insects on the stems and leaves. If at all possible, mechanically remove as much scale as possible from the stems and undersides of the leaves. Spray the underside of the leaves and stems of the shrubs with insecticidal soap; be sure to follow the directions on the label. You will probably need several applications of soap to get the plants back to a healthy condition. These holly shrubs will not get better until they are moved to a place where they receive better sunlight and air. Root prune the shrubs approximately 10-12 weeks prior to the transplanting date then dig up a foot or more outside where they were originally root pruned. Dig a plant hole 2-3 times the width and 90% of the depth of the root ball. Add nothing to the new hole site (no fertilizer or amendments). Water the plant appropriately, which is 1-2 gallons of water per inch of trunk caliper directly to the root ball. It may take the shrubs 3-4 months to get established so continue to water regularly through the spring and summer.

Mushrooms

Q:  What can you tell me about the mushrooms growing out of one of my palm trees? 

A:  I have seen the mushrooms before at the bottom of deciduous trees, but it is most unusual to see them up one whole side of a palm.  I sent the photo to the University of Florida just to be sure I was on target.  Guess what?  I was correct; the mushrooms are the fruiting bodies of Armillaria.  Armillaria root rot is a disease that decays the root system of many common trees and shrubs. It is caused by several species of Armillaria, fungi that can be recognized by the clusters of yellow to honey-colored mushrooms that emerge during moist conditions. The disease is often lethal, and infected trees may have wilting branches, branch dieback, and stunted growth. Infected trees and shrubs should be removed and replaced with resistant species. In Florida, Armillaria tabescens is the most common pathogenic species and is primarily an opportunistic pathogen, but it may kill seemingly healthy trees and shrubs in both urban and natural areas, particularly when host species are stressed. As with many landscape disorders, the most appropriate management technique is the avoidance of infection. Maintain healthy trees by using proper pruning, fertilization, irrigation, and pest management practices. One should commit to planting a more diverse landscape because they tend to better withstand pests, diseases, and even severe weather events. Symptoms of Armillaria root rot often do not appear until 1–3 years after infection has taken place. Therefore, it is difficult, if not impossible, to save trees once they become infected. There are no fungicidal cures for Armillaria. Always disinfect pruning tools between plants to reduce the possibility of transmitting diseases. Some plants with only a small area of infected roots or root collar may be saved by exposing the area to aeration, drying the fungus, and halting growth. Because Armillaria spp. can live in dead stumps and roots for years, an infected tree or shrub should be completely removed, including the stump and major roots. Removal of other susceptible trees or shrubs near the infected plant may be necessary to prevent the disease from spreading over a large area.  It is unfortunate for the palm as it will need to be removed, it will not be able to survive.  http://edis.ifas.ufl.edu/ep478

 

Q:  I have large white mushrooms all over my yard.  The grass is mostly dead or dying.  Did the rain bring these things?  What can I do? 

A: The photos you brought me are similar to the ones I took of my neighbor’s yard. Fairy Ring MushroomsThis is called “fairy ring.”  Although the name sounds cute the problem is far from amusing. The mushrooms are living on decaying material. The material may be dead and dying grass, organic amendments added to the soil before the grass was put down, dying tree roots or landscape debris buried under the soil. The first step is to remove the mushrooms immediately by hand picking them and placing them in a trash bag. The soil may be compacted and will need to be aerated. A pitchFairy Ring Mushrooms fork or metal rake can be used to break up the soil. Attached is a publication by the University of Florida regarding fairy ring which will include fungal applications.  Remember fungicides work best to protect the grass rather than cure the problem. Always read the directions on the label of any pesticide before application. Most important is to be sure to identify the problem before applying any chemical – that is the law! It may take as many as five years for the mushrooms to run out of their food source so be vigilant and patient.  http://edis.ifas.ufl.edu/LH046

Oak Gall

Q: I have these growths on the stems of my oak trees. When I crushed the growth I discovered it contained small worms. Are these killing my trees?

A: The structures are called galls and are generally caused by insects. Bacteria, fungi, mites or nematodes can cause galls to form as well. Oak GallSixty percent of all known insect galls occur in the oak family and 30 percent occur in the daisy, rose and willow families. These growths are called galls because they contain large amounts of tannin, which has a very bitter taste. Long ago, they were known as "gallnuts" because they tasted as bitter as gall. Plant galls are abnormal growths of plant cells formed as a response to the insect's stimulus caused by egg laying, or larvae or nymphs feeding. In the spring, before the leaves are fully developed, eggs are laid in the leaf or stem. Small holes on the outside of the gall indicate that the adult insects have emerged. Galls are found most commonly on the stems and leaves, but also occur on trunks, flowers, fruit, leaf-shoot terminals, petioles and roots. Each gall-forming insect produces a gall that is characteristic of that particular insect. Some galls may be two inches in diameter, while others are so small they are rarely noticed. They occur in almost every conceivable form and color, and their shapes range from spheres to tubes. The surface may be smooth, hairy or covered with spines. Although the galls often look unsightly, they will not cause significant damage therefore chemical control is usually not practical.

Q: My oak leaves have these distortions all over the leaves. What causes this?

A: Oak leaf blister is a common leaf disease among oaks in Florida and is caused by a fungus. Although infected trees may have unsightly leaves, serious damage is uncommon. The fungus which causes leaf blister attacks only the leaves, and does no damage to other parts of the tree. Spores of the pathogen infect young oak leaves. As the pathogen develops within the leaf, it causes a disruption of normal development of leaf cells. The infected tissues appear swollen or blister-like and lighter in color. Severe infections can cause the leaf to become curled or twisted. Over time the infected tissues die, leaving gray-brown areas scattered within the given leaf. Leaf blisters first appear on the underside of leaves as small, slightly depressed gray areas. Over time the infection causes the leaf to become deformed, forming a blister. The blisters can grow to be 1/3" or larger and can be seen on both sides of the leaf. There may be several blisters on a leaf and if blisters occur near the edge, leaf curl may result. Oak leaf blister is not usually noticed until many leaves have become very blistered or excessive leaf fall occurs. Any oak can be infected; however live oak, water oaks, and laurel oak are preferred hosts. Oak leaf blister was especially prevalent last season because of early spring rainy weather favorable for disease development. The fungus which causes the disease infects young leaves as they emerge, and the distinctive symptoms of oak leaf blister appear several weeks later.

Q:  Several oaks in my yard have died.  I have noticed numerous growths on the limbs, which are supposedly galls.  I want to know if they are killing my trees and if they will spread to the other trees.  I have also lost two mimosa trees. 

A:  The galls are not causing the trees to die although they may look unsightly.  It is of course sad to lose any tree but Mimosa trees are not long living trees and some are classified as invasive.  After talking to you we finally discovered what I believe the true culprit of your oak death to be – mistletoe. Mistletoe People don’t realize this plant is a parasite. As you drive down A-1A you see many of the trees along the roadside contain mistletoe and I have seen many trees all around this county full of this parasite. Totally there are about 170 species of mistletoe.  Seed dispersal is mainly done by birds.  Even though the seed goes through the birds digestive system it retains sticky hair-like structures that enable it to remain attached to the tree.  Once a seed germinates, it can penetrate the host plant by growing through the bark into the water conducting tissues.  Symptoms of damage show up first in twig dieback above the point of the mistletoe attachment.  It is interesting to note that the tree does not respond by compartmentalizing after the intrusion, which would normally occur if the tree was wounded or pruned.  Mistletoe receives water and nutrients before the host tree so in times of drought, the mistletoe causes even greater stress to the host tree.  It can live in the trees for many years but it is slowly usurping the strength out of the tree. All parts of the mistletoe contain toxic substances that inhibit protein synthesis in the intestines of humans, but the toxicity is rarely fatal. Mistletoe infections can be controlled by pruning infected branches. Branches must be cut one to two feet back of the visible infection area. Cutting only the top green portions of the plant can induce the development of many shoots in other parts of the tree so it is best to sacrifice tree limbs.

Q: What can you tell about this growth on the leaves of my oak and can you tell me what kind of oak it is? 

A:  It was difficult to absolutely identify the tree as the leaves were quite decimated by the time I was able to look at them. Chestnut Oak However, I believe you have a Swamp Chestnut Oak, Quercus michauxii , which is also known as basket oak or cow oak or the Chestnut Oak, Quercus prinus.  Both are very similar and often mistaken for each other.  Both trees reach heights from 60 to 80 feet and are native to Florida.  Neither tree has any serious insect or disease problems.  The growth under the leaf was a gall, which looks menacing but is of no real concern.  It was probably caused by an insect or fungus.  Remove any of the leaves with the gall present and you should be able to manage the life cycle.  If the tree is too tall to remove the calls, then leave it alone as chemical sprays are not necessary. 

Pesticides

Q:  Pesticide labels give a percentage of active and inert or other ingredients with percentage numbers.  I understand the active part but what does inert or others mean? 

A:   I am answering this question by using information from the EPA government website.  The EPA issued Pesticide Regulation Notice 97-6 after comments from the public indicated that consumers thought “inert” meant “harmless”.  Inert ingredients have not been defined as toxic or hazardous to humans, animals or the environment it should not be assumed inert means harmless.  According to Cambridge Advance Learners Dictionary inert means: not reacting chemically with other substances.  Hopefully that hasn’t totally scared you because inert ingredients play an important part in the effectiveness of pesticides. Inert ingredients may be used as a solvent which would allow the active ingredient to penetrate the outer surface of the plant or insect.  In some instances, inert ingredients are added to extend the pesticide product's shelf-life or to protect the pesticide from decomposition due to sunlight exposure. Some inert ingredients are added to provide at better application coverage or ease in the handling and mixing process.  Federal law requires the total percentage of inert ingredients to be listed on the label but each individual inert ingredient does not need to be listed.  It is perfectly legal to add more than one type of inert ingredient. Active ingredients are the part of the pesticide that repels, subdues, manages, kills, or controls the pest.

Powdery Mildew

Q:  What is this white stuff on the new growth of my crape myrtles? 

A:  I have received about three separate samples of powdery mildew on crape myrtlesPowdery Mildew within the last few weeks so I thought I would answer this question again.  After seeing the tree clippings brought into the office, it was easy to diagnose the problem as Powdery Mildew, Erysiphe lagerstroemiae. Powdery Mildew first appears on new shoots as a whitish powder that later spreads to the surface of leaves, stems, and flowers. Powdery mildew causes leaves, stems and flowers to become distorted and stunted. In severe cases, leaves may drop prematurely and flower buds may fail to open. Shady, humid locations and cool nights encourage powdery mildew in addition to frequent wetting of the foliage by irrigation or rainfall. Powdery mildew is most prevalent in spring and fall.
The best way to avoid powdery mildew is to plant one of the cultivars bred and selected for resistance to powdery mildew. Additionally, crape myrtle should be planted in sunny locations allowing free air movement so that wet foliage dries quickly.   The following cultivars are showing excellent or good resistance to powdery mildew:  Semi-dwarf (15 feet) – Acoma (white), Caddo (pink), Hope (blush-white), Pecos (pink), and Tonto (red).  Intermediate (up to 20 feet) – Apalachee (orange), Centennial Spirit (dark red), Christiana (deep red), Comanche (coral pink), Hopi (pink), Lipan (red-lavender), Near East (pink), Osage (pink), Osage Blush (pink), Sioux (pink), and Yuma (lavender).  Full tree (over 20 feet) – Basham’s Party Pink (lavender pink), Biloxi (pink), Choctaw (pink), Fantasy (white), Kiowa (white), Miami (pink), Muskogee (lavender pink), Natchez (white), Townhouse (white), Tuscarora (coral pink), Tuskegee (pink), Twilight (dark purple), and Wichita (lavender). 
One other point I want to discuss is the importance of having a confirmed diagnosis before applying any pesticide.  The condition on your crape myrtle is caused by a fungus therefore using insecticides would not be beneficial.  The improper application of pesticides means we are not following the guidelines set by the Federal government on the pesticide label.  In essence, we are breaking the law.  Improper pesticide application wastes time and money and can contribute to the pest resistance.  I know it is sometimes difficult to drop specimens by the Extension office but it is essential for us to provide the correct chemical for management.  For any of your plant problems attend the free plant clinics at the Yulee office (86026 Pages Dairy Rd., Yulee) – the dates are listed on our website at http://nassau.ifas.ufl.edu.

 

Scale

Q:  I have a wonderful area in my front yard with the perennial Gaura planted in it and love to watch the "sunny butterflies" dance around in the breeze.  However, this year my gaura has some sort of scale.  I pinched a piece of it and put it on my scanner and have it attached.  Each little crusty scale has a very small hole on the top - for the insect to come out of I guess.  Please let me know what this is and how to treat it. 

A:  The photo was perfect for helping indentify which of the scale insects you had onFig Wax Scale your gaura or Whirling Butterflies.  There are dozens of cultivars of gaura but they have been a favorite landscape plant of southern gardens for several years. Most of them are drought tolerant and love full sun.  The insect on your plant is called fig wax scale, Ceroplastes rusci.   It resembles a small turtle which can become as large as the eraser on a pencil.  This insect is found on a large number of ornamental plants from impatiens to palms.  Some of the scale may be dead already, especially if it is dry and crunchy.  But I would suggest you mechanically remove a much of them as you can use a stick or plastic spoon – be careful not to damage the stems.  Then apply horticulture oil anywhere you found the scale.  The plant may require additional applications to keep the insect in check– just follow the directions on the label.  It is best to use Ultra fine oil which can be used all year here in Florida.  Do not apply in the heat of the day – it is best used in the mid morning or early evening. You will have to be diligent about scouting (checking) for the return of these insects as they reproduce rapidly. You may prepare your own horticulture oil mixture by adding one tablespoon of vegetable oil and one tablespoon of mild detergent (not a degreaser) to one gallon of water.  Be sure you shake the mixture well. 

Q: My magnolia has small white specks on the leaves. What are they and how do I get rid of them?

A:Diagnosis of spots on leaves is often difficult but I was able to identify these pests easily once you sent them to my office. Believe it or not – they even survived the postal service delivery! The spots are insects called False Oleander Scale, Pseudaulacaspis cockerelli. At one time this insect was called magnolia white scale and oleander scale. It was originally detected in palms from California but quickly became established here in the early 1950s. At this point it can be found throughout Florida and most of the southern Gulf States. It has become an economic pest for many local growers and garden nurseries especially since it is found on many ornamentals such as magnolia, dogwood, sweet bay, banana shrub, Aucuba, and oleander.Scales, especially armored scales are very difficult to control when mature. The protective covering of the female prevents pesticides from reaching the eggs. Examine plants for live scales by crushing the wax cover. Dead scales do not fall from plants. If you find live scale, apply horticulture oil, which is the best method of scale management. More than one application will be required – usually within two weeks. Be sure to follow the directions on the label. If the infestation is small, you can wipe them off with a paper towel and toss the towel in the trash. Continue to watch the plant and try to catch any future infestations early.

Q: My plum tree appears to have some sort of scale on it. What can you tell me about this scale?

A: The scale appears to be a wax scale. In general, adult females spend the winter on twigs and produce eggs very early in the spring. The eggs hatch to crawlers which move along the twigs to feed on leaves. This crawler stage is when the insect is vulnerable to insecticides, but it only lasts a few days. Maturity is attained in the summer, and a new generation of crawlers is produced. Wax scale feeds on a host of ornamental plants and shrubs as well as citrus. It is best to treat this scale by mechanical removal, pruning severely infested branches and applying horticulture oil. Be sure to follow the directions on the horticulture oil label.

Q: I have a sago palm that is covered with insects. The fronds actually look as though they are covered with snow. What insect is this?

A: The insect may be a scale insect called the cycad aulacaspis scale, Aulacaspis yasumatsui. It apparently originated from Thailand but it is kept in check overseas by local parasitoids. Of course, here in the U.S. this scale has no natural enemies. In 1996 it was found in Miami, Florida infesting cycads grown as ornamentals. Aulacaspis scale has since been rapidly spreading throughout Florida and has been located in Nassau County too.This scale is difficult to manage because it is found on the roots, stems and fronds of palms. Sometimes it has been incorrectly identified as magnolia white scale but experts can easily tell them apart. The aulacaspis scale female has an orange-pink body that is short and stout whereas the magnolia white scale female has a longer body structure and beige in color. Homeowners can use horticulture oils on the fronds and trunk to help control this pest. Some systemic pesticides have been applied to sago palms but the success against this pest has been limited. It may be a combination of methods will result in better control. Be careful to use sterile procedures when pruning to avoid infesting other plants. Some pruning of cycad fronds may be beneficial but do not remove too many as this will put the plant under additional stress.

Q: I have a rubber tree which we keep in the house and I am seeing yellow blotches on the upper leaves. What could be causing this problem?

A: I was glad you brought a leaf specimen into the office because I was able to locate several scale insects on the underside. The scale insects are removing the plant juice (the green chlorophyll) from the leaves and that is why you see the yellowing on the top of the leaves. These particular scale insects are very tiny and often overlooked. In fact, even when the leaves are examined using a magnifying lens the scale insects resemble a small brown dot. You can remove the scale by using a damp paper towel and wiping along the underside of the leaf then throw the towel away. I noticed most of the scale insects were gathered along the main leaf vein so they will be easy to clean off. Once you have cleaned the leaves, spray the underside with an insecticidal soap commonly found at any garden center. Occasionally scout the undersides of the leaves check to see if any of the scale has returned then spot treat them. This should help you get this problem under control.

Q: Do you know anything about indoor Ficus trees?  I do like them very much and have three.  One has developed black leaves, and the other, while it appears to be healthy, is very sticky.  It deposits a residue on the table and carpet.  Can you help?

A: The damage you described matches that of scale insects.  These creatures do not appear to be insects because they are covered by an outer shell to protect their soft bodies.  Check for small brown specks under leaves especially along the midrib or along the stems.  The adult scale insect stays in one place so most people do not recognize them as living insects.  The sticky substance you see is really a secretion from the insects called honeydew.  The scale insect inserts its mouth parts into the plant tissue and sucks out the plant fluid.  As a result, leaves may turn blotchy and yellow and may eventually drop off.  Because of their protective coating, scale insects are difficult to control.  You can remove the sticky secretions with a leaf cleaner which is available at any hardware store.  In addition, you can spray the tree with horticulture oil and insecticidal soap once a week to help control the population.  One other place to check for scale is on the trunk and stems; treat the trunk and stem area the same as you do the leaves.  Good luck, this is a very common pest on Ficus and only diligence will help your get a handle on this troublesome pest.   

Q: I have these small white specks on the back of my magnolia leaves. Can you tell me what they are and will they harm my magnolia?

A: At first I thought it might be some sort of tea scale but a closer look made me realize it was the pupa stage of some insect. I knew we probably needed to be concerned because there were so many of them. Beneficial insects seldom have large numbers of pupa; but destructive insects often produce abundant numbers of offspring. The type of insect was difficult to identify because most insect photos show the adult and sometimes the larvae or nymph stage but they seldom include the pupa stage. As I was examining the specimens under a scope which includes a light some of the insects began to break out of their pupa because of the intense heat. These tiny (about 2mm), winged insects showed no overt markings to assist me with identification. So, I sent photo samples to Dr. Lyle Buss from the University of Florida. He identified them as male tuliptree scales (Toumeyella liriodendri (Gmelin) (Homoptera: Coccidae).  Guess what, insect photos usually don’t include the male scale either! The females are globular (a bit smaller than a pea) and are found on the twigs and/or main rib of the leaves.  The males go to the back side of leaves.  Adult male tuliptree scales are winged with a pair of filaments projecting from their abdomen.  These scales produce a lot of honeydew which will result in sooty mold covering the leaves and stems, which is often a clue to an infestation.  Tuliptree scale can be damaging to the trees sometimes killing only branches but if left unchecked the whole tree can be destroyed.  These insects are very common on magnolias and yellow poplars (tuliptrees).

Q:  What are theses black/brown growths on my Tulip Magnolia? 

A:  I have seen several scale insects this month on many young trees.  The scale you brought to me is probably the Tuliptree scale, Toumeyella liriodendri.  This scale is common on magnolias.  They are often hard to spot because of their dark brown color.  They often go unnoticed until their numbers are large enough to potentially kill the plant.  They initially prefer to attach themselves to the small twigs and limbs of young trees.  This insect is very difficult to control because of its hard outer covering.  Strong chemicals are ineffective and wasteful because they cannot penetrate the outer “shell.”  The female is underneath laying vast numbers of eggs.  When the time is right the eggs develop into crawlers which come out from under the “shell.”  It is this crawler stage that is vulnerable to insecticidal soaps or horticulture oil.  However, this stage only lasts for about 3 days and there is no way to know exactly when that occurs.  The first thing to do is scrape off as many of the scale insects you can and throw then away in the trash.  They cannot fly, so whatever you remove is gone for good.  Spray with insecticidal soap or an ultrafine horticulture oil (not dormant) during the morning hours or late evening – avoid full sun times.  Light pruning of heavily infested twigs would be appropriate too.  Follow the directions on the label as to when to reapply.  This procedure would apply for any of the scale insects found on our woody ornamentals. 

Q:  What are the white dots on my Indian Hawthorn? 

A:  After looking at a few leaves, using an eye piece, it was easy to identify this scale as Fig Wax Scale, Ceroplastes rusci.  This scale looks like a small turtle.  Its outer coating is made of a pinkish-gray wax, which is divided into waxy plates.  Fig wax scale was discovered on fig trees in Israel (Bodkin 1927) which is where it received its name.  Adult females probably live out the winter on twigs and produce eggs very early in the spring. The eggs hatch into crawlers which move to feed on leaves.  Molting produces nymphs which feed on the leaf petioles (stems) or new shoots. These nymphs mature late in the fall, overwinter on the twigs, and repeat the cycle (Bodkin 1927).  Fig wax scale has been found on fig, impatiens, oleander, pittosporum, citrus, pears, and palms, as well as dozens of other landscape plants.  Management is difficult as we usually discover them after they have built up large populations.  Using a damp paper towel, manually clean off as many of the scale as possible.  Lightly prune shrubs of heavily infested branches if necessary.  Apply Insecticidal soap or ultra light horticulture oil directly on the leaves and stems.  Use only in the morning or evening hours.  Also apply around the root area a pesticide with the active ingredient Imidacloprid.  As always, be sure to follow the directions on the pesticide label – the label is the law.