The Ten Bad Actors of Bradenton-Sarasota

by Philip Paul, CR


This document was taken from a B-SRS Bulletin, and reformatted for a standalone article. The "index" of images on this pages was added to provide quick reference, and a link, for anyone searching for the cause of a rose problem


The 10 bad actors are the fungi and pests that some days slow down our enjoyment of our rose gardens. This article is dedicated to understanding and fixing those problems. I have spent considerable time trying to look at the technology and then translate it into simple English that should be a long term helpful reference. You will note that each picture is bordered with a color. The color indicates the degree of severity that particular disease or pest has.

rouges gallery - click to get details


Chili Thrips

Flower Thrips

Red banded Thrips

Anthracnose

Botrytis

Powdery Mildew

Downy Mildew

Spider Mites

Aphids

Black Spot
Each item attempts to answer all the same questions. The biggies are: What is it, what causes it, what are the effects of it, how severe is it (color code above), what are the symptoms, How do I treat it in both a small and larger gardens (usually a matter of cost), any local area observations, and any deeper references or "HOT LINKS". Later on we list the chemicals to treat the problem, dosage and costs. You will find that having Lat Farr's Book "The Southern Queen" is the best next step for getting more detail. Secondly, you will find the Disease & Pest Reference Section of the B-SRS web site is the next deeper click in your research. To see some practical solutions, check the web site in the Member's Area and read the most recent Jim Small articles.

Since spraying is often a requirement in fighting diseases and pests, here are a couple of important thoughts not often mentioned in talks or articles on spraying.
  1. Be sure to fully cover yourself before spraying; skin, inhalation or ingestion are things to watch. Most problems occur through the skin. Be sure to cover eyes and skin.
  2. When you spray it is not required that you spray each chemical separately, most of us use a cocktail. e.g. First, I assess the garden and if I don't see any insects it is always recommended that you don't use any insecticide this time. Second I mix two chemicals for Black Spot (see the Black Spot Article) usually a contact and a systemic solution. I always add a capful of Super Thrive and I use a Southern Ag Spreader Sticker.
  3. The only time I break the insecticide rule is in the spring. I like to spray a round of Conserve just to stop any early Thrip action.
  4. In the spring I also keep a small spray bottle mixed with Conserve so that at the first sign of thrips I can spray any suspected "thrippy" buds.

I have not tried to cover all the problems, these represent the majority of what you will find in our area.


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Page 2

Rose Diseases and Insects in the Bradenton-Sarasota Area

 
What is it? Chilli Thrips Category:   Insect
In October 2005 a new thrip arrived in Florida in the West Palm Beach Area called the Chilli Thrip. It apparently came in on a Hurricane. Since that time it has migrated across Florida and on to Alabama and Texas.

What are its effects and what if I don't treat it?

IT IS LETHAL!! (Thus tagged RED)


It can destroy a bush in a very short period of time. It is the number 1 destroyer of rose gardens.
Symptoms to look for:
  1. While other forms of thrips will attack white, pink or yellow roses, the Chilli's will attack any rose.
  2. look for multiple cane die-back (see below), bud damage on a red rose is a sure sign (see right), fresh buds will become brittle and drop off, leaves curl up and turn brown then drop off (right).

How do I treat it?

Smart Steps to Control:
  • Check your roses often (every day or two)
  • Starting in April be ready to spray Conserve on the ENTIRE plant

Chemical Treatment:

Small Garden
Apply Conserve Naturalyte ® at 4TBSP per gallon to roses at the first signs
Large Garden:
Apply Conserve SC ® at 1/4 to 1/4 teaspoon at the first signs Limit to 10 applications per year for effectiveness

Observations: Consider a first spraying in April as a preventative

References and Hot Links:

  1. See Jim Small article on Chilli Thrips (on the web)
  2. See b-srs.org under Disease and Pest Reference
  3. www.doacs.state.fl.us/pi/enpp/ento/chillithrips.html

      (Aren't you glad we have hot links??)







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Page 3

Rose Diseases and Insects in the Bradenton-Sarasota Area

 
What is it? Flower Thrips and Red-Banded Thrips Category:   Insect

What is the cause?

For many years we have put up with common thrips of two types. The flower thrips are tiny insects that scrape the flower bloom. The Red-Banded Thrip is differentiated by its effect, which is to drill small holes in the side of the new buds (epidermis). It also can distort the leaves and leave dark blotches on them.

What are its effects and what if I don't treat it?

They destroy blooms and if untreated can get to the foliage. In extreme cases they can ruin an entire plant.

How severe are the results: Severe (Red)

Symptoms to look for:

Flower Thrips
Look for brown edges on the buds of light colored roses (white, pink, yellow). Blooms may not open or will open deformed. (see right)

Red Banded Thrips
Look for a small 1/8" hole as if drilled in the side of a bud. Also look for dark colored blotches on leaves (see lower right)




How do I treat it?

Smart Steps to Control:
In the spring patrol your garden often; the first signs will be brown bud tops. Immediately spray as described below.

Chemical Treatment:

Small Garden: Use Conserve Naturalyte ® and mix spray with 4TBSP/Gallon.

Large Garden: Use Conserve SC ® at 1/4 to 1/2 teaspoon/gallon

Observations:

Both Conserve products will do the job, but for the small garden the Naturalyte version is much less expensive.

DO NOT let this problem go unattended; it will destroy a whole bloom period


References and Hot Links:
  • http://creatures.ifas.ufl.edu/orn/thrips/redbanded_thrips.htm
  • http://edis.ifas.ufl.edu/MG327



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Page 4


Rose Diseases and Insects in the Bradenton-Sarasota Area

 
What is it? Anthracnose Category:   Fungus

What is the cause?

Cool, moist and spring type weather encourages the growth of the fungus. Look for wet leaves with temperatures 70 to 80 degrees.

What are its effects and what if I don't treat it?

Foliage drops off and plant production slows

How severe are the results: Moderate (Yellow)


Symptoms to look for:

DO NOT CONFUSE WITH BLACK SPOT

Initially leaf spots about 1/4" in diameter, progress to purple/brown, then to light brown with a red or purple margin. These will eventually yellow and fall off. The spots are better defined than Black Spot and will have a light colored center circle that sometimes will drop off the leaf. This last characteristic will best help define the differences with Black Spot.

How do I treat it?

Smart Steps to Control: Know the difference between this disease and Black Spot, but treat them about the same with chemicals

Chemical Treatment:


Small Garden: Try Immunox or Orthenex. If there is no success try one of the "Large Garden" chemicals.

Large Garden: Eagle 20EW, Compass or usual Black Spot remedies

Observations:

Anthracnose does appear in our gardens

References and Hot Links:

www.b-srs.org Section on Disease and Pest Reference





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Page 5


Rose Diseases and Insects in the Bradenton-Sarasota Area


 
What is it? Botrytis Category:   Fungus
 

What is the cause?

Fungus grows in high humidity at temperatures between 65 and 75 degrees

What are its effects and what if I don't treat it?

Dead blooms

How severe are the results: Moderate (Blue)



Symptoms to look for:
Buds and early blooms turn to a "gray mold" color and never produce
Lat Farr reports that this often shows up on "bare root" roses, beware! I had it happen on a potted rose from out of state recently

How do I treat it?

Smart Steps to Control:
  1. Lat Farr recommends -"Plant roses where they will receive morning sun"
  2. When you notice remove affected stems & blooms
Chemical Treatment:
Small Garden:Same as below
Large Garden: Dithane M45 or Mancozeb

Observations:

This fungus appears more often than most observe.

References and Hot Links:


Lat Farr "The Southern Queen" P46-47
www.b-srs.org Section on Diseases and Pest Reference


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Page 6



Rose Diseases and Insects in the Bradenton-Sarasota Area

 
What is it? Powdery Mildew Category:   Fungus
What is the cause?
Temperatures between 65 to 70 degrees and 98% humidity and Warm days and cool nights are ideal for the growth of the fungus

What are its effects and what if I don't treat it?
Flowering may stop and bush growth will become stunted. Buds that open are distorted

How severe are the results: Moderate (Yellow)


Symptoms to look for:
  • Blister like spots on younger upper leaf surfaces
  • Young leaves become twisted and a white powdery substance appears
  • New buds may be deadThe disease starts on the upper part of the plant and works its way down

How do I treat it?

Smart Steps to Control:
  • Plant you garden with good air flow and avoid crowding
  • If possible remove the canes showing the symptoms
  • Clean up old leaves from the ground
  • Use fungicides early to get maximum help, not after a heavy infection

Chemical Treatment:


Small Garden: Immunox, Remedy (Potassium Bicarbonate)
Large Garden: Eagle 20EW, Banner Maxx, Honor Guard, Compass, Rubigan, Mancozeb

Observations:

An occasional problem in our local gardens, not an every year occurrence

References and Hot Links:

www.b-srs.org, section on Diseases and Pest Reference


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B.S.R.S.Bulletin June 2008 Page 7



Rose Diseases and Insects in the Bradenton-Sarasota Area

 
What is it? Downy Mildew
Category:   Fungus
What is the cause?
Downey Mildew occurs with moist cloudy conditions, brought on by wind and or water in COOL & DAMP WEATHER, humidity around 85% with temperatures between 65 and 80 degrees. All roses are susceptible . What are its effects and what if I don't treat it?
Can kill a bush if not treated

How severe are the results: Severe (RED)

Symptoms to look for:
Purple, red or brown spots on leaves, stems and/or blooms. Angular blotches. Starts in the top of the bush and moves lower, usually shows dead buds
How do I treat it?

Smart Steps to Control:
  • Remove & destroy any heavily affected areas of plant
  • Reduce humidity below 85% if in a controlled environment
Chemical Treatment:

Small Garden: Spray with Mancozeb every 3 to 5 days until spots are gone.
Large Garden: Mancozeb, Subdue, Compass

Observations:
An occasional actor in our environment, but serious when it appears

References and Hot Links:
www.b-srs.org Disease & Pest Reference Section on the site


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Page 8



Rose Diseases and Insects in the Bradenton-Sarasota Area

 
What is it? Spider Mites Category:   Insects

What is the cause?

These mites hide in mulch or soil around roses. They multiply in the heat and dry weather and can do great damage. The spider mites suck the sap from leaves, starting the process. Often CRs will tell you that mites get their start in well sprayed gardens because the insecticides indiscriminately kill both the good and bad insects, thus giving room to spider mites.

What are its effects and what if I don't treat it?

They will defoliate a bush and may cause dieback if not completely kill the bush.

How severe are the results:Can kill bush - SEVERE (RED)

Symptoms to look for:
Lower foliage will lighten up. Put a towel or sheet below the bush, then shake and look for small dots. They can also be seen with a magnifying glass on underside of leaves.

How do I treat it?

Smart Steps to Control:
  • Inspect leaves regularly, look on the undersides!
  • Use a water wand and blast both sides of every leaf
  • Use the water wand every 2 or 3 days

Small Garden: Use the water wand first, and then a miticide
Large Garden: Use a miticide such as Avid, Forbid, Floramite SC (All VERY expensive), see Southern Queen for more information.

Observations:

Keep looking at the underside of leaves in hot weather

References and Hot Links:

Lat Farr "The Southern Queen" P48-49
www.b-srs.org, Diseases and Pests Reference and then mites.



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Page 9



Rose Diseases and Insects in the Bradenton-Sarasota Area

What is it? Aphids Category:   Insects

What is the cause?

Aphids are small, 1/8" or less, insects. They may vary in color from green, yellow, brown, red, black or white depending on the species and the plants they are feeding from. They seem to travel in colonies so they are easy to distinguish.

What are its effects and what if I don't treat it?

Aphids do reduce the plants ability to have adequate photosynthesis. Seldom are they a threat to the plant. They do stunt new growth and can deform the plant.

How severe are the results: Insignificant to moderate (Blue)


Symptoms to look for: Aphids thrive during the "Purple Time of Year" (the spring or fall). They love the new blooms and will leave the leaves with "Honeydew" which is the sap from the leaves they cannot consume. The substance makes the leaves sticky and it is easy to notice.

How do I treat it?

Smart Steps to Control:
The first and usually the only step is to keep up the use of a water wand.

Chemical Treatment:

Small Garden: As above water wand, if not successful try insecticidal soap
Large Garden: If they prove stubborn, use Mavrik, Merit or Malathion may work

Observations:

Aphids truly embody the term pest. In our area the water wand should work. Lat Farr says that systemic sprays work better than contact sprays

References and Hot Links:

Lat Farr's Book "The Southern Queen" P48




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Page 10



Rose Diseases and Insects in the Bradenton-Sarasota Area

 
What is it? Black Spot Category:   Fungus
 

What is the cause?

Excessive moisture on the foliage of the plant that lasts for more than 9 hours allows the fungus time to infect the leaves. Early evening rain, late day watering or heavy dew can be a primary cause. Spores are often on the ground and watering can splash them on the foliage.

What are its effects and what if I don't treat it?

Loss of attractive foliage, difficult to bring in the house or exhibit. When the leaves are gone, the ability of the plant to absorb necessary sunlight disappears

How severe are the results:

Eventually bush slows production and generally looks bad

How do I treat it?

Smart steps to control:
  • When planting don't crowd the roses, leave air space between bushes
  • When pruning optimize air flow in the bush
  • Never water roses 2 hours or less before sunset (time to let the foliage dry)
  • Remove infected leaves from plant and ground, always spray ground as well as bush
  • Be sure to remove old Black Spotted leaves from the garden (trash) If all the lower leaves have fallen off , it may be time to re-prune

Chemical Treatment

Small Garden: Use Orthenex Spray Can or Immunox Insect & Disease Control Spray These are Systemic Fungicides only. You may still need a Contact Spray.
Large Garden: To PREVENT Black Spot, Banner Maxx or Honor Guard alternated with Cleary's 3336 or Compass. These are SYSTEMIC Fungicides which protect the body or inside of the plant
To KILL existing Black Spot spores use Mancozeb (Liquid) or Diathane M45 powder). These are CONTACT Fungicides (protects leaves)The spray program should be planned as a weekly activity.


Observations:

This is a nationwide problem; it is the number one issue in our area. Almost all roses are affected by Black Spot. Some are less so than others. There is no total cure for Black Spot.

References and Hot Links:

  • ARS Magazine "American Rose" May/June 2008
  • The Fungus Among Us Lat Farr's "The Southern Queen" P43-45
  • B-SRS Web site section on Disease & Pest references.