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 to 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 904 548-1116, (904) 548-1182,– 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). 
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.
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 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
- 
and
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.
Mold
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;
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.
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. 
Sixty
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: What are these growths on my oak leaves and will it kill my tree?
A: NO. The growths are called galls, which are a common occurrence on oaks in our area. Gall tissue is formed when the plant reacts to insect or mite egg laying process. Galls can also be formed when bacteria or fungi enter into the plant through a natural or artificial opening. The insects or mites inside galls become surrounded by a food source and are protected by the gall tissue; therefore no chemical sprayed on the outside of the plant will be effective. The biggest problem with gall-infested plants is they are sometimes unattractive and make take away from the overall beauty of the tree or shrub. Galls formed on leaves do not stop the production of food for the plant and only occasionally do the leaves drop early. Twig and stem galls usually persist for more than a year. They, on the other hand, can weaken stems and twigs and therefore a tree or shrub limb may be more susceptible to breakage during storms. The galls formed on your oak leaves were caused by a tiny wasp. Often these wasps, which are so small they may be mistaken for gnats, are instrumental in keeping populations of insect pests in check. They do not bite or sting humans or animals so there is no need to use a pesticide.
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. 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. 
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.
Scale
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.