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FAQs

Crape Myrtles

I have white powdery fuzz on the leaves of my crepe myrtle, how do I get rid of it?

powdery mildew on crape myrtle

You have powdery mildew. Some crape myrtle varieties are susceptible to this fungus. Shade and over fertilization can also exacerbate the disease as well as over head irrigation. Chemical control with a recommended fungicide may be needed. Make sure to read and follow labeled directions and warnings. More….

My crape myrtle tree has two different flower colors, some flowers are pink and some are pure white.   Why?

Growing crapemyrtles in nurseries typically involves placing several small plants in one pot in order to create a “multi-stem” crapemyrtle. It is not uncommon for growers to mix up their crapemyrtle plants; when they are not flowering, many of them look alike. I suspect this happened to some of the plants purchased by this home owner. The pink-flowering form may have been slower growing than the white-flowering form, so it took longer (or more fertilizer) for this form to start flowering.       Another possibility is that crapemyrtle seeds sprouted at the base of the white-flowering plants. Crapemyrtles don’t come “true” from seed, so it is very likely the young plants would be pink. Again, it probably took a few years to get large enough to flower. The home owner should be able to follow each pink-flowering branch back to a main trunk (or trunks, if more than one). If they wish, they can out the pink-flowering form (but they will re-sprout, and so will need to continue to do this for years).

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Citrus

What’s causing the leaves of my citrus trees to be curled and crinkled?  Two Possibilities: (1)Citrus Leaf Miner Damage — This insect is the caterpillar of a tiny moth that lays eggs on the leaves. The caterpillars hatch from the eggs and “mine” their way through the leaves causing them to cup and crinkle.  “Squiggly” lines can also be seen in the affected leaves. This insect is not harmful to the health or fruit production of established trees. Young citrus trees may benefit from sprays of horticulture oil which deters the moth’s ability to lay eggs on the leaf. Spray each time a new flush of growth appears.  Read the label of oil products carefully, as horticulture oil can burn the leaves when applied. incorrectly.  (2) Aphid Damage – Curled, distorted leaves can also be the result of aphid insects.  These pests have needle-like mouthparts which pierce the leaves and feed on the plant sap.  They always feed on the newest, most tender growth.  As these leaves mature, they exhibit the damage, but by then the aphids are long-gone.  Aphid damage is mostly aesthetic and can be ignored.  If aphids are detected, they can be easily controlled by forceful sprays of water or by insecticidal soaps.  

The leaves of my citrus tree are covered with black “stuff.”  Is it hurting my tree? You probably have “sooty mold.”   Sooty mold appears as a black, sooty growth on the upper side of leaves.  It is a mildew that is harmless, but indicates that an insect was, or is, present (usually aphids, whiteflies or scales).  As these piercing-sucking insects feed on the undersides of the leaves, they secrete a sticky, clear fluid called “honeydew” that drops onto the leaves below.  Sooty mold grows upon this secretion.  Treat the insect pest problem and the sooty mold will go away.  It can also be washed off with a forceful stream of water.

The fruits on my citrus tree are splitting and falling off.  There are little bugs in the fruit.  What can I do to prevent this?
It is probably a water or varietal problem. The problem of splitting fruits usually occurs in the early fall.  At this time of year, the citrus fruits are mature in size and the peel is not expanding.  If heavy rains occur, citrus trees absorb water and force it into the fruits.  The peel cannot expand, and instead splits.  The fruit will begin to decay and attract insects.  Splitting fruit is also associated with young trees and certain varieties.

Something is chewing holes in the leaves of my citrus tree. Will it hurt my tree? Usually the chewed holes are either a grasshopper or caterpillar. Damage is usually contained to a small proportion of leaves and should be ignored.  The caterpillar is called an “orange dog“and is the larval stage of the beautiful Giant Swallowtail Butterfly.

orange dog caterpillar

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Herbs

What kind of herbs can I grow in my garden?  Most of the common herbs can be grown seasonally in Florida in sufficient quantities for home use. Since only a small portion of the plant is usually needed at any one time and because the plants are generally small, herbs are adapted to container culture. More…

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Houseplants

My house plant has white cottony things on the leaves and/or stems. How do I treat it?  You may have mealybugs on the plant. They can be controlled easily with insecticidal soaps or oils.

The lower leaves of my house plant have turned yellow and begun to fall off. What is the problem with my plants?  The plant may need fertilizer or repotting if it has been in the same soil for a prolonged period.

My house plant is wilting, what am I doing wrong? It may need more or less water. If the soil feels dry at a depth of 4 to 6 inches, consider watering the plant thoroughly and on a more frequent basis. If the soil is very moist, over-watering could be the culprit. Allow the plant the dry out more between waterings. Also, remember to use pots with holes in the bottom and drain the catch basin after you water.

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Lawns

Should I leave my grass clippings on the lawn or should I have a catch bag on my mower?  If you are mowing frequently enough, it is best to leave the clippings on the grass to recycle the nitrogen in them (as much as 1 to 2 pounds per year– the equivalent of 1 to 2 fertilizations per year). Mow often enough so that no more than 1/3 of the grassblades are removed. The small amount of clippings generated from frequent mowings will not contribute to thatch.

How often should I water my grass?  When is the best time of day to do this? It is nearly impossible to say how many times a week a lawn should be watered since so many factors will influence this. Thus, it is best to water on an “as-needed” basis or when the grass shows signs of stress from a lack of water. Some of those signs are:

  1. The grass color will be a bluish-gray rather than a clear green.
  2. Footprints will remain for a long time when the grass is walked on.
  3. Grass blades will fold in half.
  4. Soil samples from the root zone feel dry.

A general rule for watering is to apply 1/2 to 3/4 inch of water two times per week in the summer and once every ten to fourteen days in the winter (in the event of no rain). The best time for lawn irrigation is in the early morning hours (between 2am and 8am) to avoid prolonging the dew period which can encourage disease problems.

Should I apply lime to my turf? What type of fertilizer should I use?  Only apply lime if needed as indicated by soil testing. Contact your local Extension Office for more information on how to get your soil tested and to determine if lime is needed. Extension Offices also have kits available that you can send to Gainesville to decide what type of fertilizer and how much lime should be applied.

I have brown spots and/or large dead patches of grass. What do I use to control the fungus or insect that is causing this damage in my lawn?  There are many fungi and insects that can cause symptoms like these as well as some other issues. Contact your local Extension Office.  They may ask you to bring in a sample for examination. The sample should consist of about an 8 inch by 8 inch piece of sod with 2 to 3 inches of soil beneath. The sample should also be taken from the edge of the affected area so that both healthy and disease grass are present.

I have planted grass plugs to establish a new lawn and weeds are coming up between the plugs.  Is there a weed killer that can be used to kill the weeds that is safe on the grass?  I cannot recommend a weed killer at this stage of growth.  Newly establishing grass is more susceptible to herbicide damage.  Do as much mechanical weed control as is practical.  This means hand pulling and hoeing between the plugs until coverage is complete.  Begin mowing as soon as the plugs have grown about an inch above the suggested cutting height.  Frequent mowing will help to control many of the broadleaved weeds.

I have some gray ashy growth on my grass but my grass doesn’t seemed to be affected.  What is it?

slime mold

You have slime mold.  It does not directly harm turfgrasses or plants.  Since they most often occur during wet weather, they disappear rapidly as soon as it dries. 

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Landscape Plants

My roses have black spots on the leaves and the leaves are falling off. How should I care for them?  You probably have a fungus called black spot, which should be treated regularly on non-resistant rose varieties using recommended fungicides. Make sure to read and follow labeled directions and warnings. More….

I have white spots on the leaves of my plants/trees, what should I use to treat them?  If the spot rubs off easily, you may have a scale insect. They can be treated easily with insecticidal oils. Make sure to read and follow labeled directions and warnings.

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Mulch

How do I control the weeds in my flower garden?  The use of mulch is an effective tool to fight the annual weeds in a landscape bed. Use an organic mulch such as pine straw, pine bark or melaleuca mulch.  Make sure to use enough to cover the ground with a 2 to 3-inch thick layer after settling. Don’t pile mulch up around the bases of plants. It is best to pull the mulch away from plants stems and trunks so that the mulch does not promote rotting. Also, leave a one foot mulch free zone away from your house to prevent pest problems.  More…

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Palms

What type of fertilizer do I use on my palm?  A slow-release fertilizer with the numbers 8-2-12 +4MG (magnesium) with micronutrients should be used on palms in our area. More….

There is white fuzz on my sago palm leaves, especially the undersides. How do I kill it?   You have an infestation of scale insects. First spray the scales off with a water nozzle to remove dead and loose scales. Then use a horticultural oil to control the scales. Make sure to read and follow labeled directions and warnings.

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Trees

My Japanese magnolia leaves turn brown and have spots on them in the summer, what should I spray my plant with?  No spray is needed. Japanese magnolias tend to prefer a more shady environment and don’t tolerate our sunny, hot summer days so the leaves get spots and become less attractive. Make sure to rake up and discard the leaves and petals that fall.

My dogwood trees look horrible, why don’t they do well?Dogwoods are understory trees and prefer the shade of larger trees. They tend to get leaf scorch and other problems when planted in sunny areas. Clean up after the leaves fall to help prevent some of their problems.

My pine trees have begun to turn yellow and brown. There is sawdust collecting at the base and I can see holes with sap coming out. What should I do?  You may have an infestation of Southern pine beetle. The only option once they have infested a tree is to have it removed. It should then be burned or hauled away so that other pines are not infested. A pest control operator can spray trees with preventive chemicals before they are infested. The best prevention is tree health and thinning of stands of pines if they are to dense, make sure not to damage others in the process.

I would like to grow Magnolia trees from seed.  How is this done?  Gather seeds in the fall as soon as the fruit is ripe.  Remove the soft outer pulp and plant immediately.  They can also be stratified – stored under moist conditions for about 40 degrees F for 3 to 6 months.  In either case, do not allow the seeds to completely dry out.  Avoid saving magnolia seed at room temperature over the winter.  Indoor conditions would result in the loss of viability.

 

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Tomatoes

Why have my tomatoes stopped bearing fruit?   Pollination is necessary for fruit formation.  Tomato blossoms are perfect flowers, containing both male and female reproductive parts and are capable of pollinating themselves.  A physical means such as wind however, is needed to move the pollen.  Pollination occurs within a narrow temperature range.  An ideal night temperature is between 60 and 70 degrees.  As night temperatures approach the mid-seventies in the summer, plants continue to flower, but cannot pollinate properly.  So, it’s the hot nights that stop the plant’s summer fruit production.

Even with optimal environmental conditions, tomatoes may have difficulty setting fruit when excessive nitrogen fertilizers are used.  With high nitrogen, the plant becomes overly vegetative and will not produce flowers necessary for fruit production.

According to Dan Mullins, there are some exceptions.  Some of the “hot set” varieties fruit somewhat longer than the standard types.  The small fruited, or cherry, tomatoes continue fruiting to some degree throughout the summer and Chelsea, yielding an intermediate sized fruit, bears long into the summer.

My tomato leaves have curled up, what’s the problem?Tomatoes can develop a disorder called a “physiologic leaf roll.” It causes the lower leaves to roll upward and become thick and leathery.  This disorder is usually associated with heavy applications of nitrogen fertilizers, root pruning (digging too close to the roots) and pruning of the tomato plant.  While it looks disturbing, physiologic leaf roll does not reduce plant growth or yield.  Interestingly, even if all cultural practices are corrected, the leaves will continue to stay rolled.

Why is my tomato rotting on the bottom? Blossom end rot is due to a shortage of calcium in the fruit.  As the fruit enlarges, the plant’s water need increases.  If the plant doesn’t receive adequate water or if there are soil moisture fluctuations, plant growth slows and nutrient uptake is reduced.  In addition, because the nutrient calcium is carried in the plant’s water stream, those plant parts that are transpiring the most (the older, larger leaves) will receive the calcium.  Developing fruit is the least likely to receive the calcium it needs resulting in a typically dark, shriveled lesion always at the blossom end of the fruit. 

blossom end rot

To avoid blossom end rot, avoid applying nitrogen in the ammonium form since it appears to negatively affect calcium uptake.  Also, ensure that the plant receives adequate and consistent water.  Timely and repeated spraying of tomato fruit and foliage with a calcium chloride solution may be beneficial.  

 

What’s causing my tomatoes to crack?  There are two types of growth cracks that will occur at the stem end of the tomato:  concentric and radial.  Concentric cracking will produce circular cracks around the stem end of the fruit.  Radial cracks spread outward from the stem end.  Cracks typically appear as the fruit enlarges and matures.  Cracks are the result of extremely rapid fruit growth.  This rapid fruit growth may be brought on by periods of abundant rain, especially after a dry period.  Cultivars vary in their susceptibility to cracking.  Very susceptible cultivars will crack when green.  The earlier the crack develops, the deeper the cracks will become.  Proper plant nutrition and consistent, adequate irrigation will reduce the likelihood of cracks.

Why are my tomatoes puffy and malformed?   This is a condition known as “catfacing.”  The affected fruits are puckered with swollen projections and/or can have deep cavities in the fruit.  The cause is the abnormal development of the flower.  Some conditions that negatively affect flower development are extreme cold or heat, drought, improper fertilization and/or exposure to herbicides.  There is no control of catfacing other than to follow proper cultural techniques and keep the herbicides away from tomato flowers.

One day my tomato plant was beautiful and full of fruit and the next it was totally wilted even though I’ve watered it, what’s wrong?  This is where is gets tough trying to make a good diagnosis.  Many pathogens cause wilting.   One wilt disorder is caused by bacteria.  It causes a rapid collapse and death of the entire plant.  It is most severe in moist, warm, high pH and low fertility soils.  To make the diagnosis, cut through the stem near the ground.  The center of the stem (pith) will be dark and water-soaked.  Suspend the stem in a glass of water.  If it is a bacterial wilt, white milky ooze will appear within an hour.

bacteria (white flow) streaming from a cut stem

I have many tomatoes on my plants but fear that they will rot due to the rains that we are receiving.  What should I do?Regular applications of an approved tomato fungicide will help to protect them.  Avoid handling plants or picking when the foliage is wet.  This can spread rot and blight diseases.  Also, consider picking them as soon as they start turning pink and allow them to finish ripening indoors.  The eating quality will not be reduced significantly if they are picked in this stage. Don’t place those that are pink in the refrigerator.  Wait until they are fully ripe if they must be refrigerated.  The development of flavor ceases once they are chilled.

What is a Japanese tomato ring?  Ever wonder why your best tomato plant is the one that came up in the compost pile, instead of among the ones being nurtured in the garden? There are several reasons why this occurs, and you can recreate this same growing condition by installing a Japanese tomato ring.Start by purchasing a ten foot long piece of concrete reinforcing wire that will be used to make a large cage. The wire should be 5 feet wide, with a 6 inch mesh size. Join the ends together and tie securely. This will form a cage that is slightly over 3 feet in diameter.Select a sunny location for installing the tomato ring. You will need a circular area that is about 6 feet in diameter. Spade and turn the soil in this area to a depth of 8 inches. Smooth the surface by raking and place a 6 inch deep layer of compost on the soil surface.Stand the wire cylinder upright on top of the first layer of compost and secure the base with short stakes. Sprinkle one-fourth cupful of dolomite lime and the same amount of a balanced garden fertilizer over the surface of the compost. Add a 6 inch deep layer of leaves, followed by another layer of compost, plus lime and fertilizer.Continue alternating layers of leaves and compost until the material on the inside of the wire reaches a minimum height of two and one-half feet. The top layer should consist of leaves. Shape the top layer so that it is concave, with the center being about 2 inches lower than the outside edge.Place a cupful of fertilizer on the surface of the top layer of leaves, in the center of the pile. Water from the top in order to thoroughly soak the pile.Set tomato plants in the ground on the outside, and within 2 inches of the base of the wire. A 3 foot wide cage will allow room for 4 plants to be evenly spaced around the outside edge.Mulch the plants with a 3 inch layer of leaves. Also, mulch a 2 foot wide band around the base of the cage. Keep plants watered until they are well established and the roots begin to grow into the material inside the cage.Subsequent irrigation is done by applying water to the top, in the center of the pile. This allows for complete watering and movement of the fertilizer without wetting the foliage and stems.This system has several other advantages. The alternating layers of compost and leaves provide a highly organic medium and plenty of air for the roots. And, no separate staking is required. As plants grow, simply tie them to the wire.This is a space saving technique with the potential for producing heavy yields of tomatoes. If other tomato growing methods have been unsuccessful for you, give this one a try.

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Vegetables

I have been told that I need to lime the soil in my vegetable garden.  How long should I wait before it is safe to plant?  The lime of choice is dolomite or dolomitic limestone.  It is slow acting, long lasting and will not damage seedlings or young plants when used as recommended.  I hope that you are applying lime based upon a soil test, rather than on someone’s opinion.  Don’t reapply lime unless a sample from the garden again shows the need.

My radishes produced well until late May.  At that time they stopped, and began forming stalks and flowering.  What caused this?  Radishes are grown as a cool season, or winter vegetable, in our area.  High temperatures during spring and summer cause them to flower and go to seed.  They should be seeded from September through March in gardens along the Gulf Coast.  Several other vegetables must also be grown as winter vegetables because they do not tolerate our spring and summer heat.   These include: broccoli, brussels sprouts, cabbage, carrots, cauliflower, kale, kohlrabi, leek, lettuce, mustard, onions, parsley, spinach, strawberry and turnips.     

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