Two Months Post-Irma, We’re Still Learning
The first couple of weeks following the storm were busy for everyone. When you first see an orchard hit by a hurricane or tropical storm, it’s a bit overwhelming. The ground is littered with limbs and lime green with what looks to be most of your crop.
That’s if you’re lucky.
The less fortunate would find trees down. Some by the hundreds, some by the thousands.
At this point, I’m tired of picking up limbs, tired of talking about this storm and its damage. Most growers are tired of cleaning up their orchards. By the time you read this most of that will be done, at least to the point that harvest can proceed. And I would suspect that if you talked to any Georgia pecan grower, they may tell you about some of their damage, but every one of them would tell you they are very thankful.
On Sept. 10, we were just hoping we would still have trees left. While we lost some trees and a lot of nuts, most growers still have a good crop left to harvest. It could have been much worse.
As we should do with most bad experiences, it’s important to learn from this storm to try to prevent future tree loss.
Since many of the trees we lost were in the age range of 5-15 years, I’ve been asked more than once: “Should we not irrigate young trees to develop a better root system?”
The answer to this question is really based on economics.
Sure, not irrigating the tree and forcing its roots to search a little more for water may develop a deeper root system. But it is likely that an irrigated tree has more of a root system. It’s just a little shallower, depending on exactly how much you water.
One thing is for sure, the top of a young, non-irrigated tree will be smaller than a young, irrigated tree, and this is likely what makes the most difference because the non-irrigated tree presents a smaller sail to the wind.
I don’t think irrigation method makes a big difference either. I have heard it proposed that micro-sprinkler irrigated trees are more likely to be blown over than drip irrigated trees, but in seeing a lot of this over the past month, I don’t see that irrigation method plays a big role in the loss of trees.
If you are growing pecans commercially, it’s a no-brainer to irrigate young trees. It increases growth by 300 percent and gets the trees into production at least three to five years faster, which is the key point. The orchard pays for itself much more quickly. I wouldn’t base my decision about irrigating young pecan trees on the chances of a storm taking out the trees. You are much more likely to lose trees to drought stress or ambrosia beetles if you don’t irrigate them than you are to lose irrigated trees to a storm.
Besides irrigation, planting depth is also something to examine when looking to protect against storm damage. Certainly not all, but many of the trees we lost, fell because of the age-old problem of planting depth. If trees are dealing with 70 mph winds, even a strong tree with adequate brace roots can potentially fall, but those without brace roots will be the first to go down.
This is why I tend to place so much emphasis on planting depth when speaking about orchard establishment. It’s better to plant too shallow than too deep for this reason. The grafted portion of the tree will not develop roots so if you plant the tree with the graft several inches below the soil line, you won’t have any brace roots on that tree. I plant every tree with the upper most lateral root at the soil line or no more than an inch below. This ensures you don’t plant too deep.
In addition to managing the planting depth, the top of the tree needs to remain in proportion with what the root system can support. This is the most significant thing you can do to protect trees from loss to storms. Meaning you don’t need to push them too hard with nitrogen, and you should prune trees often. You will not harvest nuts from the trees within the first three years, so use this time to develop the root system. From a fertility standpoint, this means focusing less on nitrogen and more on phosphorus and zinc fertility, both of which are required for root growth. These nutrients should be built up in soils where new orchards are to be planted.
Also, to help prevent blow downs from storms, you can conduct central leader pruning in the first few years and then keeping the inside of the tree fairly open after that. Also, one of the most interesting things I have observed is that based on what we saw with our hedging trial, hedged trees suffered about 60 percent less damage than non-hedged trees in the form of large broken limbs and downed trees. This is another good reason to consider hedging as a part of your orchard management.
The storm is behind us though. And as clean-up ends, I hope everyone has a good harvest!