Best Fungicide recommendation

Hello Everyone,

It's been a strange 8 months and here's hoping you all are healthy and safe.

This summer, because of extreme drought and high heat, we lost a couple of trees to fungi. Although the problem was spread out over our front and back yards, a few plants were able to survive through the application of Neem oil.

Here we are in the fall and I'm seeing it again in one of our adult willow trees. After cutting off all the parts that had the infection and spraying with Neem oil, two weeks ago, I saw some of the fungi had returned today.

Is there a better/best fungicide I can try instead of Neem oil?

Thanks very much!

Best,
MR2

 

Spraying trees of any size is extremely difficult. How big were the trees you lost and how big are the ones that remain. How and what equipment were you using to apply the neem oil? What type of fungus did/do you have? It's rather odd to have a fungal problem with high heat and dry conditions.

 

Thanks, Pilot.

First, I agree it's odd. We are in Tucson and what set us off on a fungus track was a referral we made when we brought some infected branches into our local University of Arizona Ag. Extension Office. Although the people there could not identify the particular ailment, the consensus was it was a fungus and furthermore, that Neem oil was the solution. After mixed results over the last 8-9 mos., we're revisiting the matter.

Secondly, the tallest of the trees we lost was about 12 ft high and the rest were between 6 - 8 ft. tall. I used a Flowmaster 2-gallon sprayer ( https://www.homedepot.com/p/RL-Flo-M...02HD/100350719 ). Spring came very early to Tucson and in March, I stood on a ladder and sprayed till the leaves were wet and the solution was running down the bark of larger branches and trunk. I repeated after 14 days. Then we left for about 4 months. This brings us back to the timeline in my first post.

Thirdly, after the spraying, but for no correlation other than timeline, some of the plants and trees recovered. Meantime, we had also decided to either drastically trim or cut down to the ground a couple of plants which we thought could be salvaged. Our immediate thought was to stop the spread of whatever it was. some of those that were cut back (bauhinia) and especially the hopbush that was cut down to stubs on the ground have come back healthy and visually free of any infection.

I am going to take some photos of healthy vs infected branches and post them for better analyses.

More later.

 

Good leaf
Close up of disease top. Above, good leaf.

 

As to the link between drought and fungus, surprisingly, there's lot of information online about the connection.

Drought Stress and Tree Diseases

https://apsjournals.apsnet.org/doi/p....2001.85.7.745

https://www.echo-ca.org/article/tree...caused-drought

https://www.kansasforests.org/forest...ght-stress.pdf

 

Yea, stress is always an invitation to disease. Just like people, when you are strong and healthy you are less likely to get sick.

I was asking about your spraying because I had someone in my town ask me to come look at their tree. They had been treating it with neem and weren't seeing results. I went over and saw their 40' tall tree that they sprayed twice with a pump sprayer similar to yours. Needless to say they were only treating the bottom 10' of the tree nowhere near often enough.

Fungal infections can be tough, especially in trees. Sometimes the only solution is to plant something resistant to you fungus. The fungus I see most here on the east coast is Verticillium wilt even in trees. It lives in the soil and can survive for many years and is always present to some degree in my area. Simple supportive care like water and mild fertilizing works as some trees can outgrow a infection.

Most plant problems are rarely one and done things. They often take frequent applications, sometimes forever if your plants aren't resistant to the disease. Are your oil applications frequent enough?

Are you open to chemical fungicides?

 

In brief, no, and yes. Additionally, I will have to review the irrigation settings to determine whether it should try to compensate for the shortage of rainfall. During my work with Biosphere 2, it was clear from experiments that lack of water in combination with elevated temperatures led to various insurmountable diseases. Maybe the fungus is just s symptom of a more systemic problem.

I would appreciate your recommendation for a chemical fungicide

Over the long run, we don't think there is any choice other than to cultivate only species which can adapt to the changing climate. We have already replaced our lost trees (one of which was a willow, just as pictured) with varieties which can survive full sun and minimal irrigation.

 

It sounds like you already know what needs to be done. I'm sure you know that fungicides work prophylactically. They are good a prevention but don't work so well at curing a tree after a disease is visible.

I enjoy gardening and love doing tropicals and trees not suitable to my climate. I'll grow a specimen or two for several years doing whatever it takes to keep it alive. For chemical fungal treatment I use Propiconazole which is available under several brand names. But, I realize that if I need the fungicide I'm likely fighting a loosing battle. In your case spraying might be something you do for a couple years with new trees until they become established and able to fight off infection on their own.

 

Thank you very much for being a great sounding board, Pilot Dane Many times the solution is right before me but needs another person to point it out.

I'll try Propiconazole, as suggested.

Much appreciated,
MR2