Gardenia's with holes in their leaves

[Spanky]

I have two gardenia's along my property line, next to a wooden fence. They were growing beautifully for years and reached a height of about 15'. A couple of years ago, they began dropping leaves and hardly had any blooms. I began noticing the leaves getting holes in them but couldn't see any bugs. Have fertilized with a product that is a systemic bug killer, which worked the first couple of times. However, it doesn't seem to help anymore. I have researched gardenia diseases and pest problems but my plants don't match any of the descriptions I've found. I am posting pictures in the hopes someone can point me in the right direction for a solution. The leaves get a small black spot, the spot grows and turns yellow, and then the leaf material shrivels and falls away, leaving a hole. Any help is appreciated. Thanks!

 

[Becky]

Welcome to the forum Spanky! Great to have you here

Sorry to hear about your gardenia. It doesn't look like insect damage, so my money would be on either a fungus or bacteria. How do the branches look? Anything unusual? There is something called Bacterial Canker that causes spots on leaves to go brown then fall out, but as far as I know it only affects Prunus trees. Looks similar to what you've got though.

 

[Chuck]

It is a fungal leaf disease not insects or bacterial.

 

[Spanky]

Thanks for the quick responses! I think fungal is probably correct. These gardenia's are sandwiched between two houses and fences. In addition, we had pavers layed next to them and (as I recall), that's when the current problems began. I don't think they're getting enough air circulation or ground evaporation to let them dry, especially during the long, we summers here in Florida. Unfortunately, I don't know how I can fix that particular aspect of the situation. So is there a particular anti-fungal spray or other product you might recommend?

 

[Chuck]

Thanks for the quick responses! I think fungal is probably correct. These gardenia's are sandwiched between two houses and fences. In addition, we had pavers layed next to them and (as I recall), that's when the current problems began. I don't think they're getting enough air circulation or ground evaporation to let them dry, especially during the long, we summers here in Florida. Unfortunately, I don't know how I can fix that particular aspect of the situation. So is there a particular anti-fungal spray or other product you might recommend?

Understanding your limited alternatives of dealing with fungus there are 3 ways to deal with the problem. One, is to figure out a way to add air circulation, two is to use anti-fungal chemical sprays or three is to fight it with an organic means. Being as how I never use chemicals I will tell you how I would address the problem. I would start a spray regimen using cornmeal tea. This cornmeal is NOT the cornmeal you use to coat fish or make corn bread out of. This cornmeal is called by different names. Stone Ground, Whole Ground, Horticultural or Agricultural are the names you look for. If the cornmeal you find has the word Enriched anywhere on the package this is NOT what you want. What you do is get a container, probably about 2 1/2 gallons if the tree is 15' tall, put about 2 cups of cornmeal into a sock or panty hose or cheese cloth and soak it for about 36-48 hours and spray the entire tree, top to bottom and both sides of the leaves. Really soak them. Also sprinkle dry cornmeal around the base of the tree. This cornmeal is the favorite growing medium for a fungus called Tricoderma. Tricoderma is a fungus that attacks and kills harmful fungus. Spray this solution once a week until ALL symptoms have disappeared. It may take some time

 

[Chuck]

Understanding your limited alternatives of dealing with fungus there are 3 ways to deal with the problem. One, is to figure out a way to add air circulation, two is to use anti-fungal chemical sprays or three is to fight it with an organic means. Being as how I never use chemicals I will tell you how I would address the problem. I would start a spray regimen using cornmeal tea. This cornmeal is NOT the cornmeal you use to coat fish or make corn bread out of. This cornmeal is called by different names. Stone Ground, Whole Ground, Horticultural or Agricultural are the names you look for. If the cornmeal you find has the word Enriched anywhere on the package this is NOT what you want. What you do is get a container, probably about 2 1/2 gallons if the tree is 15' tall, put about 2 cups of cornmeal into a sock or panty hose or cheese cloth and soak it for about 36-48 hours and spray the entire tree, top to bottom and both sides of the leaves. Really soak them. Also sprinkle dry cornmeal around the base of the tree. This cornmeal is the favorite growing medium for a fungus called Tricoderma. Tricoderma is a fungus that attacks and kills harmful fungus. Spray this solution once a week until ALL symptoms have disappeared. It may take some time

Another thing that is happening is that all those paver bricks are restricting the oxygen to the roots of the tree, just like putting a concrete slab over the roots of an established tree such as an oak. What do you want more, the bricks or the tree? You can have the tree and a weed free, mud free area by using decomposed granite which you can easily and cheaply obtain.

 

[Spanky]

Chuck,
Thanks for your in-depth response! I'm afraid my altruistic side is out-weighed by the pragmatic side who paid a lot of $$ to have those pavers installed. I will do my very best to nurture these gardenias back to health, but they'll have to do so with the pavers in place. Hopefully, my thread question and your replies will help someone else in a similar situation. Thanks again for your assistance!

 

[Spanky]

Well, it's been a couple of months and I'm happy to report our gardenia's are doing great! Used copper treatment for the fungal infection and then doses of iron and 10/10/10 fertilizer to rebuild their strength. Turns out gardenia's don't like having their roots covered with cement pavers and crushed concrete paver base material. Apparently that's what put them on their heels in the first place. I also did some trimming of the surrounding foliage to enhance air flow around the gardenia's to keep the humidity factor as low as possible. Thanks again to all who offered advice and comment!