I'd check for Eastern Tent Caterpillars. They are hatching out here in southern OK and will eat many different kinds of foliage, although on our property they tent to be most common on plum trees. That would be my first guess, especially if new leaves are continuing to come out even after the other leaves have fallen. I have sprayed them and killed them on my fruit trees, but I bet they also are on other trees in the yard and I haven't noticed them yet.

You can read more about tent caterpillars and their control in this document from OSU. It is several pages down in the document:

OSU: Eastern Tent Caterpillar

If you have been having above-average rainfall recently and if your soil drains slowly, it might be the excess moisture, which sometimes causes red oak leaves to drop. This is just a stress reaction to the roots being wet and as long as they get a chance to dry out, the trees recover.

If your leaves that are falling are pretty much uniformly green, that lends credence to the cause of the leaf drop being something simple like the two options I mentioned above.

If the edges of the leaves are turning brown before they fall, you should at least read about Oak Wilt (a fungal disease that can kill all oaks but to which red oaks are particularly susceptible) and make sure that what you are seeing does not seem like oak wilt. (If it helps to know this, oak wilt has been almost epidemic in TX for at least the last decade, but not so much here in OK).

TFS: Oak Wilt

Hope this helps.

Dawn

Thanks. Yes, basically green drops which is not as likely to be oak wilt. Never seen a tent caterpillar on our property or near it in 3 years we've lived here, but, do see some individual threads on the tree. Hah, the rain is a tiny fraction of last year, when I exceeded on my property 100 inches of rain. Have just not been able to find any of the crawlies on it when I look. I did find some sort of flying bug on a partial eaten leaf. Did not get a picture of know what it was, strange looking.

Should I treat for the scale on the tree though? I was not aware oaks get scale.

Yeah, using the Neem oil extract which supposedly works when leafed out. When I got to thinking about it, 5 of my trees came from a local tree farm less than a mile from my house. All 5 of those trees show scale! Maybe they had an issue there. No other tree has any in my yard. They are not very tall oaks yet, so, hopefully, once I get rid of all of them (scale) won't have so much a problem moving forward.

Only 78" huh? Desert!

Caterpillars, still have not found one. Maybe they are there, not sure. They'll get eaten anyway. Unless they get that web going.

The sad thing was that 78" of rain (as I am sure you know) can be just as damaging for garden plants as a year with 18 or 20" of rain. Aside from the garden and farming issues, our county courthouse flooded (and it wasn't the only place that flooded, just the most well-known) on a May 2015 day when we got about 12" of rain in some parts of the county (including our house) and a lot of roads were flooded, washed out, wiped away, etc. I think all of the roads had been repaired and reopened.....and last week's flooding got some of them and now they are washed out, destroyed and closed again, and unlikely to be repaired until after the spring's storm season has passed at the very earlirst.

While we think of a rainy season as being a good year, it still can do a lot of damage. Sadly, that was not even the first day my garden has been subjected to 12" in one day, but it was the first time that's happened since April of 2009. It is aggravating to have a river of rainwater running across your property, but no less aggravating than drought or wildfire. Here in Oklahoma, the land of extreme weather (a title Texas could claim as well), we always seem to go from feast to famine to feast in terms of rainfall. Last year's rainfall was epic, and I hope we don't have that sort of year again this year. It is starting to look like April 2016 bears too much of a resemblance to 2015 in that respect.

Scale seems prone to move in and attack stressed trees. Being recently transplanted in the last couple of years and then being blasted by too much water could have been the stress that led to scale attacking your trees. If they were my trees, even after I'd eliminated the scale this year, I'd probably spray them with a dormant oil next winter during the dormant season just to prevent any surviving scale from reappearing next spring. It's better to be safe than sorry.

I was looking at flood damage along the Red River yesterday, including formerly thriving winter wheat crops buried under silt and floodwaters, and thinking to myself "here we go again". We almost bought land adjacent to the river and talked ourselves out of it, instead buying close to the river but on high enough ground that our house would be very unlikely to flood. Every time the river floods, I am grateful we made that decision. I can handle a flooded garden and yard, but wouldn't be happy to have a flooded house, and even in last year's worst possible case flooding scenario, our house was never at risk of being flooded. Our yard and garden were buried under pond-sized puddles for weeks and weeks at a time though. As plants leaf out (or, more accurately, don't leaf out) this spring, we're learning what did or did not survive the flooding, and I am shocked at how few plants apparently died.

Yeah, plants seem to be amazing resilient. I did lose some, but, it's not as bad as I expected. Some I can now try and start more of on my own, added experiment this year before having to buy and replace them.

I am definitely going to dormant oil them this coming winter.

The problem for me with 100" of rain was keeping my semi new trees upright. The ground was just practically water at times, and the trees tended to want to just fall or tilt at times. Staking was almost useless, would have needed a 5' rod. My elm seems to have cracked below ground, not sure that will be able to be saved. I guess I will get something harder to replace it this fall if need be.

At least there is this several day break as it has given me a chance to try and get some of the scale. At least my Arizona Cypress show no sign of bagworms yet, had lots last year. My swallows have moved in, so, hopefully, they'll be on patrol for various pests.

This year has got to be better. If we stay as wet this year as last year, the trees will have to learn how to swim and the people will start growing webbed feet.