Since late May, I’ve seen a number of trees between the ages of 2nd and 4th leaf suddenly crash. The leaves remain on the tree after turning completely brown. All of this is during the dry and hot spell. It is essentially as if something is clogging the vascular system in which the leaves starve for water. There are a number of things that are causing these trees to crash.
Ambrosia Beetles
First, scout for Ambrosia beetles. Many of these dying trees are the result from a late flight of these beetles. Remember, trees that are under some type of stress are attacked by beetles. Attacks can happen anytime during the season. It is easy to identify when you pull back the tree guards. If you do not see the obvious signs of ‘toothpicks’, look more closely for tiny, holes in the bark. Remember, tree death from Ambrosia beetles is a function of how many attack the tree and tree size. When the tree cannot move water through the cambium due to bore holes, these trees crash. What if you cannot find any ‘toothpicks’ and holes?


Freeze Damage
The second thing is likely to be freeze damage. Freeze damage can show up long after it actually occurs. In younger trees, cold temperatures affect the cambium below the bark. When temperatures get low and stay low for a considerable time, a section of the cambium dies. As it dies, the tree is not able to move water through this point. In March of 2023, we had a late spring freeze for a number of days. Once the sap rises up the trunk, the water inside the cambium froze. These trees initially do not show an issue. As the cambium dies and collapses, the bark will sink in. You generally see a longitudinal crack at the damaged location. This may take months to occur. Not to mention, the trees do not have a high water demand in the early season. Once temperatures get hot and the demand for water increases, the freeze damage takes effect. These trees suddenly crash. I believe damage from cold is causing



Effects of Hurricane/Tropical Storm
If you do not see visible signs of Ambrosia beetle and/or freeze damage, there is a good chance that roots of these trees were damaged by last year’s Hurricane Idalia. The site below was right in the line of this storm back in August of 2023. What happens is when winds blow through and trees are rocked back and forth, some roots will brake even if the trees do not fall over. That root loss will cause the trees to gradually decline and sometimes crash when the root system is not capable of handling the tree. The capability of that root system is fully challenged when it gets severely HOT and DRY. This weather has pushed these trees.

Flat-Headed Apple Borer
Something else to look for is damage from another beetle called flat-headed apple borer. Overall, I would say I see this insect 10% of what I see from Ambrosia beetle. If Ambrosia beetle damage is 5 – 10% at its worse in a year, then flat-headed apple borer is 1 – 2%. I do not see them in every orchard. When I see them, they seem to be sporadic and only attacking a few trees. Also, many times where I find the damage, the trees are actually growing well. The beetle infects the tree around a year old. It’s larvae bore inside the cambium. Unlike an Ambrosia beetle, its larvae do feed on the tree. This is why imidacloprid can be used against them. Nonetheless, they definitely kill trees if they borer around the trunk enough. Usually damage is close to the ground about a foot high. The damage looks pretty ugly, as if a knife cut into the bark and peeled back the bark.
