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mowyo
11-26-2009, 11:51 PM
Trimmed shrubs at one of my commercial customers this week and noticed some black-looking stuff on the leaves.looks like diesel exhaust.Nearly all privits and foster hollys with plenty of air space around them.The plants all seem to be very healthy.It's not as bad on the sunny side of the building. We
've had a very wet sept. and oct. here.
I have a pesticide training manual from U of Tn. and nothing really looks like this stuff .Powdery mildew is closest match but it's white or gray.
Also these guys are not going to spend a whole lot on this right now.
Thanks in advance for any ideas.

44DCNF
11-27-2009, 12:57 AM
Could be sooty mold. Photos would help to narrow it down for you, but that's something you can check online or in your manuals . Are there elm trees nearby/overhead that are infested with elm flea weevils? They will leave tiny holes in the leaves and the leaves drop all season long. Even if not, it could be sooty mold due to the dampness. Research that to see if it looks like it. The beetles (and other leaf mining pests) exude a substance called honeydew as they eat bore through the leaves, as well as the leaf bits they chew, and their feces. The honeydew feeds this mold. Of course it could be other things but that has been real common here with the wet weather and weevils. Makes a mess of cars, siding, roofs, it's on everything around and under the infested trees.

Smallaxe
11-27-2009, 09:23 AM
Do an image seach from several different search engines, using the names, just given.
Then be sure to post your pictures and let us know. :)

Think Green
11-27-2009, 11:40 AM
Mowyo,
By what you stated, the plants on the sunny side of the building are fine!
The homes in my county estate; the ones that have the back doors facing the north are covered with mold. The neighbors that have landscapes facing north all are experiencing mold issues even on the sidings. Not an uncommon problem in moist seasons.
Be sure that the Fosteri Hollies aren't pitted in the leaves as the mold usually only covers the surface and can be scratched off with the fingernail. Sometimes, cottony scale will cause sooty mold development, so look and make sure there is no cottony looking insects on the undersides and stems of the leaves. Legustrums are another problem with the ailment. Thick dense growing shrubs with large foliage is often succeptible to the ailment.
IF no insects are present, you can take a hose end sprayer attachment; add some dawn to the bottle and spray all the visible foliage, stems, branches to dissolve the mold. Be carefull of the pressure of the sprayer as to not damage any leaves or in our case here, remove the berries on the hollies. Often I will spray a large shrub and allow the soap to dissolve the mold and move on to the next shrub. I them return to the first shrub and do the spraying again. It is like prewetting you car to loosen the dirt before you wash with a cloth. Usually the second application will do the trick! After the soapy water has cleaned the leaves, take the attachment off and freely run clean water over the plants to wash off any excess soap. Rinse off the grass or any nearby plants around the treated area.
I have had some customers try to use a powerwasher on their plants to remove this mold, so I would not even advise it: I wouldn't have mentioned it but I know that some people are thinking it anyway!!! Don't do it!! Don't use bleach either!!!
I wouldn't mention these thing on this panel but I have seen people do it only to destroy their plants.

Mold is part of moisture, shade, pollutants, and dust collections.!

Think Green
11-27-2009, 12:00 PM
I don't like to double post but my pinkie finger hit the enter button!!!!!!!!!! Sorry!
To really answer you question, yes it is a fungus. To go further look for aphids on the holly or privet. Our Southern weather patterns have been crazy---warm weather, cool weather, then warm again. Seasonal patterns will erupt odd insect patterns. Aphids, scale, and other leaf invading insects cause sappage and will cause this sticky mess on the leaf surface. The sooty mold grows fungus and can damage the plants if left unattended in the central areas of the plant as light cannot penetrate the leaf surface. Some plants yellow out and have leaf drop. There are other factors and indicators of leaf damage or sooty mold problems. If you suspect this is insect damage, then the other thing to do is use Safer's Soap or Insecticidal Soaps to clean the plant surfaces.
Read the label before you purchase the products and dawn is cheaper and will perform the same process.

mdlwn1
11-27-2009, 12:46 PM
Scale is massive this year.....ANY scale secretions will lead to mildew...not just cottony scale.

mowyo
11-28-2009, 09:23 AM
thanks for the replys.did some more checking and it does look like sooty mold.no overhead trees,so any bugs have to be on the shrubs.they may be gone as we've had a few cold nites.i'm going to check next week for bug damage, although a sharp-eyed landscape guy should have spotted this when he trimmed them....

Kevin M.
11-28-2009, 01:26 PM
This is classic symptoms of scale on the hollies and sounds like could be white flies on the privet. The sooty mold is caused by the excretions of both insects and both are also dormant right now since it is too cold for them to be active. If you have a spray license you can spray these insects right now with dormant oil. I have sprayed for scale and white flies numerous, numerous times and have had great success with it.

RAlmaroad
12-01-2009, 03:14 PM
I have a property that has some of the same type of sooty mold on Carolina Jasmins in semi-sun and under an overhanging Live Oak tree. I have a photo, but have to work out how to get it from the phone to the computer. So never seen the mnold before and after using the Dawn Dishwashing Detergent and spraying down with water, I'm wondering if the ground should not be treated with Heritage or another type of fungicide. Any suggestions?
Roy

greendoctor
12-01-2009, 11:56 PM
Check under the leaves of the Jasmines. What you might find there are scale insects, whitefly or mealybug. The other possibility are those same pests in the tree above the plants. At this time of the year, it is ok to apply 1-2% horticultural oil at high pressure to the affected plants. Another approach that works well and is probably a good idea if the trees are too tall to spray is a soil injection with Merit. This also works on shrubs.

heritage
12-02-2009, 12:18 AM
Check under the leaves of the Jasmines. What you might find there are scale insects, whitefly or mealybug. The other possibility are those same pests in the tree above the plants. At this time of the year, it is ok to apply 1-2% horticultural oil at high pressure to the affected plants. Another approach that works well and is probably a good idea if the trees are too tall to spray is a soil injection with Merit. This also works on shrubs.

Hi Green Doc,

All good sir. I have had better results when it comes to scale pest control using Safari in Place of the Merit using the same method...Soil Injection.

It is the same Chemical Family but the particle of the Safari when in soil solution in 1,000x smaller than the merit.

This gives the Safari the Ability to move through the Phloem of the plant where many of the armored scale settle/feed on the sugary sap.

The Merit wont flow down through the Phloem...too large of particle.......If it was super small like the Safari, it would do the trick.

This has worked better for me dealing with scale.

Pete

greendoctor
12-02-2009, 12:42 AM
For armored scale or insects residing in big trees, I like Safari for its speed of action. I do need to balance that with longevity. It does me no good to have plants reinfested withing a year. I do have a 365 day growing season, so something that lasts a while is a plus. Here, Safari is good for about 60-90 days. Merit will last 12 months plus. I have known some guys locally who will make up an injection that contains both. :eek: The only things that work faster than Merit or Safari are dimethoate or Metasystox-R. Can't use dimethoate in residential areas and I would cause all kinds of controversy using Metasystox. Besides, I do not know of anyone willing to pay me enough to handle that stuff.