By Julie Christensen
Pecan trees (Carya illinoinensis) are as beautiful as they are useful – growing 75 to 100 feet with a wide spreading canopy. Pecan trees are hardy in U.S. Department of Agriculture plant hardiness zones 5 through 10, although they are most commonly grown south of zone 7. In northern climates, they don’t bear nuts reliably.
Pecan trees can be damaged by many things, including poor, heavy soil, frost or high winds, and of course, disease. Treating diseases on full-grown trees is difficult because of their size. In most cases, prevention is a better strategy. Use disease-free seedlings and provide well-draining, light soil. Water the trees regularly during dry conditions to avoid drought stress.
Blotch
Large black or yellowish spots on the leaves are the main symptoms of blotch. This disease is rarely serious, but in some cases, it can defoliate the trees in late summer. It appears mostly on drought-stressed trees or trees with zinc deficiency.
Keep the trees healthy through proper watering and conduct a soil test to check for any nutrient deficiencies. Rake up and discard leaves in the fall to prevent the disease from overwintering.
Crown gall
This nasty disease causes brown or white nodules to form around the roots of the tree. As the disease progresses, the roots rot and the tree slowly loses vigor and dies. Unfortunately, there is no treatment for the disease. Buy disease-free trees from a reputable nursery and plant them in loose, well-draining soil. Do not plant pecan trees where crown gall has been a problem previously.
Powdery mildew
Powdery mildew affects many plants from lilacs to pumpkins to pecan trees. It appears as a white coating on the leaves and is rarely serious. It is most common in young seedlings. Use drip irrigation rather than overhead sprinklers to prevent its spread. If the condition is severe, treat it with the fungicides recommended for scab (see below).
Rosette
Rosette is caused by a zinc deficiency. In infected trees, you’ll first notice yellowing leaves in the tops of the trees. Later, leaves become small and entire branches may die back or become defoliated. To treat this condition, spray the leaves with a solution of 1 tablespoon zinc sulfate per gallon of water. You can also add zinc to the soil for a longer lasting solution. Make applications based on soil test results or at a rate of ½ pound per inch of trunk diameter. Spread the zinc evenly on the soil from the trunk to the drip line.
Scab
Scab is one of the most common diseases to infect pecan trees, depending on where you live. It first appears as damage to the leaves and nuts. Leaves develop olive brown splotches on the undersides of the leaves. As the disease progresses, the upper sides of the leaves develop markings, as well. In severe cases, the tree becomes defoliated, which can weaken the tree and reduce pecan production.
The nuts also develop olive-brown, velvety splotches on the husks. In some cases, the entire husk becomes covered or the nuts drop prematurely from the tree.
Although fungicides are available, the average home grower lacks the equipment necessary for application. Instead, your best strategy is to plant disease resistant varieties, such as Cape Fear, Desirable, Elliott and Chickasaw. Fungicides labeled for treating scab include Benlate 50WB, Enable 2F and Orbit 3.6EZ. Follow all package directions carefully and make applications every three weeks from the time leaves first emerge until the shells harden.
Wood or heart rot
These fungal diseases enter pecan trees that have been injured by storm, improper pruning or damage during home construction. Once the fungus enters the tree, it slowly rots the wood, weakening and eventually killing the tree. To prevent wood or heart rot, prune the tree regularly to remove branches damaged by ice or wind. Use proper pruning techniques and avoid ripping the bark.
For more information, visit the following links:
Evaluating Pecan Problems from Texas A and M University.
Pecan Diseases from Clemson University Extension.
Julie Christensen learned about gardening on her grandfather’s farm and mother’s vegetable garden in southern Idaho. Today, she lives and gardens on the high plains of Colorado. When she’s not digging in the dirt, Julie writes about food, education, parenting and gardening.Â
I have some pecan wood that I got for cooking on the grill. After getting it all stacked, I noticed some white fungus (or something) growing on some of the cut ends. It looks, & feels like some kind of foam. Is it ok to cook with????
yes no problems
I would like to sent a picture to you to get your opinion on my pecan trees color
our pecan tree has a big hole in the side. looks like something has been eating on it. what , if anything, can we do to try and save the tree.
the bark on the trees are falling off leaves had brown spots do bores invade pecan trees limbs falling off. live in east texas sprayed for spiders and afids help
My pecan tree bears pecans when the pecans fall from the tree the meat is dried up! We never get to eat the pecans???
I’m having the same problem have you found a solution to this? If you have I would appreciate any help
water water and more water
water water water,, if nut is dried up or just partially field in then most likely a water issue, im in South Texas just north of Alice and its been over a 100 here the past 2 weeks, Im watering 8 to 10hrs a day right now per tree about 300 to 400 gallons per tree a day
add zinc to make kernals grow normal sprinkle around the tree some out to the drip read the directions on zinc bag may help
My pecan are falling and turning black
pecans are black and falling off early not getting any pecans
I have this problem to and am seeking answers
Same problem as patricia black spots on fruit, fall off
Small bunches of brown leaves 1 – 2 feet in size, 40 – 50. Foot tree with scattered bunches
Pecan trees have large, white web looking things all over them. About 10 of theses on tree. They are about 2 feet by 2 feet round bunches of webs. What is this and how do we treat?
THe white webs are web worms. The best way to get rid of them is to cut the webbed branches down, disturbing the webs as little as possible. Then burn the webs/worms. Sounds crazy, but it works.
Caterpillars.
We live in the south and both our pecan and walnut trees get them. From what I’ve read, there’s not a lot you can do, especially since they are so high up. We will usually cut out the branches that have the low-hanging ones just so we don’t walk into them.
Maybe somebody will post with some helpful suggestions.
Yellowjacket wasps are natural enemies of the web worms.
Those worms spend the winter under ground, so spray the ground 2 or 3 times just before spring. Also put a greased rope about 3 feet off the ground around the trunk, will stop them from climbing back up. They return every spring when the breeze blows, but it’s better now
Our pecan trees have small drilled holes in the trunk with a powdery like fine sawdust emitting down the trunk and are dying off. I have no clue as to what is causing this.
We live in Louisiana………
Did you get any feedback about your question?
I have the same problems with no clue
My dad’s pecan tre3 has several holes ” looks like they were drilled into the tree near the trunk. Also some kind of yellow mossy looking substance. My grandmother started the sapling from a nut. It’s been growing 10 years now. My grandmother is no longer with us, so the tree is super important to my dad. Can you help me figure out what is wrong? I would be forever grateful.
My 70 yr old pecan in the front yard (only tree in the front) has finally seen it’s last year. Between the diseases, web worms, falling (trunk size) branches, and the wildlife living in it, we’re done. As far as the holes and dust, I’ve had generations of red headed woodpeckers (still) in mine, and yes, they do that. I live in the middle of suburbia, in the middle of Alexandria La! There must be 4 or 5 squirrel families, including albinos, along with cardinals, blue jays, mocking birds, and doves constantly making homes…the tree is now maybe 40 ft. high with all that has fallen…time to go, but I worry about the habitat. We live on a street that has lots of mature trees, and I’m hoping they can relocate safely.
Oh I really hope something convinced you to keep the tree around! Woodpeckers need dead trees too. But I suppose logically keeping a dead tree around just won’t work in every yard though. My parents are both from Alexandria!
2 of my old pecan trees are losing their leaves from the bottom up and it’s June! There are new sprouts growing all over the tree though. Not sure what’s happening?
My trees look healthy but the pecans turn black and fall off..The ground is covered with black pecans..Any body got the answers or treatment fir this?
I am having the same problem as Patricia. This is the second year this has happened. I do not want to lose the shade from this tree as it is wonderful in the summer, Actually the only shade tree in my back yard, but I cannot continue to deal with the falling black nuts. Any suggestions for treatment would be greatly appreciated. I live in the southern coastal area of Virginia and wonder if the humidity have anything to do with it. This tree is over 50 years old,and after reducing the squirrel population, had great hopes of getting some nuts for ourselves. Not happening. HELP, Please!
My pecan tree haves big wood looking stuff growing out at the bottom, they almost look like black rocks
Can you tell me what is going on with my pecan tree? The leaves are brown with the vein still yellow. I would like to send a picture to you. I can’t seem to find anything on the internet to identify the problem.
Hi,
I bought a pecan sapling three years ago at ou local nursery. For the last two springs here in Green Valley, Az, the tree sprouts leaves and the green flowers. Well, the leaves grow but the flowers shrivel, dry and fall off. I give it plenty of water, the leaves a green. What gives? We have huge pecan orchards less than a mile from here. Why are the blossoms on my sapling turning brown and falling off?.
I have a pecan tree thata 5 years old. the leaves has some kind of green growths on them. can you tell me what this is and how I can get rid of them. I don’t want my tree to die.
I also have a tree about 6 or 7 years old, with growths on some of the leaves. The look sort of like a small green bloom that is starting to open up. Did you find out anything about them? I appreciate any info you might have. Thanks.
my pecan tree is about 5 yrs old. i have alot of green little nodules that are growing thru the leaves. it doesnt look like its turning the leaves any color but i want to know what i can treat it with so it doesnt kill the tree. any help would be appreciated.
Spray for insects.
They cause these lumps on the leaves.
My tree had them, spray them, and this year, I haven’t seen any on the leaves. Spray the trunk as high as you can too.
I’m in MS. I have a lot of pecan branch ends down, looks like a strong wind came through and shook the trees. Near the end if the leaf stems, where they detached from the branches, there are some dime sized brown nodules. Most have a small hole in them, so I am guessing that something has hatched, crawled out and ate the ends off of the branches. Some of the nodules look to have some fine dirt in them. Any ideas?
I have a 35 year old hican tree to my knowledge it has only beared nuts once . This tree is very big with bright healthy green leaves. What can I do to get it to bare nuts again? I was also told that a hican was a cross between a hickory nut tree and a pecan tree . Is this true?
I have a pecan tree that’s approximately 50-60 ft tall and very wide limb length in my backyard that was here when I moved in in 2013. It produced lots of nuts but were rotten when they hit the ground, also has lots of holes and leaks a sappy substance. I considered having it cut down and use the wood for cooking but now I’m wanting to save it. It hasn’t produced anything in a couple of years. Any advice or tips can get from anyone? Also I’m thinking about planting another one but I don’t know what kind have now and according to the reading it has to be a different kind. Any help or advice for this would be grateful. Thank you in advance.
Our pecan trees have had the webs of worms, and its affecting the nuts. Other than cutting the webs out of the trees, can you spray them with something? My trees are over 60 feet high!
The nuts have a stilts white on the outer shell.
My pecan tree has little red and green balls where the pecan should be never seen these before
I planted four pecan saplings in the spring with peat moss. They did great at first but now in July the leaves are turning brown and falling off. The temp has been in the 100’s here in southeast Texas for a while. I was watering them every day but now I’m worried that may be too much or is it not enough? Any suggestions?
Something is eating my pecan tree leaves and some limb ends have turned brown and you can see threw them. Located in southwest Louisiana.