Pecan trees are native to Texas and for good reason; they are also the official state trees of Texas. These resilient trees are drought tolerant, and not only survive but thrive with little to no care in many areas. However, like any tree, they are susceptible to a number of issues. Why do pecan trees drip sap? Read on to learn more.
If your pecan tree has sap dripping from it, it probably isn’t really sap — although in a roundabout way it is. A seeping pecan tree is more than likely afflicted with pecan tree aphids. The seeping from the pecan trees is simply honeydew, a sweet, charming nomenclature for aphid poop.
Yes, folks; if your pecan tree has sap dripping from it, it’s probably the digestive remnants from either the black margined or yellow pecan tree aphid. It appears that the pecan tree is leaking sap, but that isn’t the case. You have an infestation of tree aphids. I’m betting you are now wondering how you can combat an unwelcome colony of aphids on your pecan tree.
First off, it is best to arm yourself with information regarding your enemy. Aphids are tiny, soft bodied insects that suck sap from plant foliage. They ravage many different types of plants but in the case of pecans, there are two types of aphid foes: the black margined aphid (Monellia caryella) and the yellow pecan aphid (Monlliopsis pecanis). You may have one, or unfortunately both of these sap suckers on your pecan tree.
Immature aphids are difficult to identify since they lack wings. The black margined aphid has, as its name implies, a black stripe running along the outer margin of its wings. The yellow pecan aphid holds its wings over its body and lacks the distinguishing black stripe.
The black margined aphid attacks in full force during June to August and then its population abates after about three weeks. Yellow pecan aphid infestations occur later in the season but can overlap the black margined aphids’ feeding grounds. Both species have piercing mouth parts that suck nutrients and water from the veins of the leaves. As they feed, they excrete the excess sugars. This sweet excrement is called honeydew and it collects in a sticky mess on the foliage of the pecan.
The black pecan aphid causes more devastation than the yellow aphid. It only takes three black pecan aphids per leaf to cause irreparable damage and defoliation. When the black aphid is feeding, it injects a toxin into the leaf that causes the tissue to turn yellow, then brown and die. The adults are pear shaped and the nymphs are dark, olive-green.
Not only can large infestations of aphids defoliate trees, but the residual honeydew invites sooty mold. Sooty mold feeds on the honeydew when the humidity is high. The mold covers the leaves, reducing photosynthesis, causing leaf drop and possible death. In any case, the leaf injury reduces yields as well as the quality of the nuts due to lower carbohydrate production.
Yellow aphid eggs survive the winter months harbored in bark crevices. The immature aphids, or nymphs, hatch in the spring and immediately start to feed on the emergent leaves. These nymphs are all females that can reproduce without males. They are mature at one week and give birth to live young during the spring and summer. In late summer to early fall, males and females develop. At this time, the females deposit the aforementioned overwintering eggs. The question is how do you control or suppress such a durable insect enemy?
Aphids are prolific reproducers but they do have a short life cycle. While infestations can increase rapidly, there are some ways to combat them. There are a number of natural enemies such as lacewings, lady beetles, spiders and other insects that can reduce the population.
You can also use an insecticide to quell the aphid horde, but keep in mind that insecticides will also destroy the beneficial insects and may possibly allow the aphid population to increase even more rapidly. Also, insecticides do not consistently control both species of pecan aphids, and aphids become tolerant to insecticides over time.
Commercial orchards use Imidaclorpid, Dimethoate, Chlorpryifos and Endosulfan to combat aphid infestations. These are not available to the home grower. You can, however, try Malthion, Neem oil and insecticidal soap. You can also pray for rain and/or apply a healthy spray of the hose to the foliage. Both of these can reduce the aphid population somewhat.
Lastly, some species of pecan are more resistant to aphid population than others. ‘Pawnee’ is the least susceptible cultivar to yellow aphids.
Much like the veins in our body, the tree's vascular system transports sap. This is a sugary liquid filled with water and nutrients that are carried throughout the tree via the phloem and xylem. Phloem carries nutrients from the leaves to other parts of the plant, while xylem carries nutrients upwards from the roots.
Sap is produced in the leaves (or needles) of a tree and is distributed throughout the tree through the phloem, which runs vertically from top to bottom on the tree. If a cut is made in the trunk or a branch of a living tree, the cut severs some of the phloems, allowing the sap to ooze out.
The amount of sap in the tree varies based on the time of year. In some varieties, the sap levels are especially high in early spring. If you make pruning cuts at that time, the tree may bleed sap. This isn't usually too much of an issue, but it's best to avoid it so you can prevent problems like gummosis and tree decline.
Ако от вашето дърво от орехче капе от него сок, той вероятно не е сок – макар и в кръгово движение. Просмукващото се орехово дърво е повече от вероятно засегнато от листни въшки от орехови дървета. Просмукването от пекановите дървета е просто медена роса, сладка, очарователна номенклатура за въшки.
Да, хора ако от вашето пеканово дърво капе сок от него, вероятно това са храносмилателните остатъци от черната периферия или жълтата листна въшка от пекан Изглежда, че ореховото дърво изтича сок, но това не е така. Имате нападение от листни въшки. Обзалагам се, че сега се чудите как можете да се борите с нежелана колония от листни въшки на вашето орехово дърво.
There is no cure for slime flux, but trees are able to compartmentalize the disease to keep it away from healthy branches. Remove dead bark and loose bark so the area beneath can dry. Wash the sap off the surface of the trunk or branch, and apply insecticidal spray to reduce infestations by insects. Avoid wounding your tree. Minimize pruning and don’t cut behind the ridge of bark that forms in the branch crotch. Horticulturists used to recommend drilling a hole in the trunk and letting the sap drip out through a pipe inserted into the hole. This treatment was supposed to help relieve pressure. However, it doesn’t help the tree to heal any faster, and may even aggravate the condition by spreading the disease to other parts of the tree.
Oh Christmas Tree. Oh Christmas Tree.
should I cut down the trees and start fresh?
Ailing Dogwood Tree - HELP!
Interesting. I haven't seen any aphids but it is as you describe. It's not just under the pecans, it's also under the cedar elm, but not the other trees. Everything is shiny and sticky.
I know this happens every year - we've seen it before - but I've never paid attention to how long it lasts or how easy it is to remove since I've never had anything that mattered getting covered. well, except the car and that we have to wash. I just don't want to figure out how to wash off the patio stuff then do it again a week later. I guess I'll wait awhile. Maybe all this hard rain will wash it off.
I have a northeast-facing garden. It is planted with a crape myrtle and miniature rose bushes and I have spread crushed pecan shells as a mulch. I have found that a vivid yellow substance appears under the pecan mulch and sometimes in small "piles" on top of the mulch. What is this stuff.
What you have seen is probably a very interesting organism called "slime mold". It is not a fungus but more like a protozoan. Spores germinate into small (microscopic) organisms that move around, feeding on decomposing organic matter (your pecan shell mulch), then on cue all of these things move together to form the bright yellow structure that you saw. At this time some become spore cells and others become part of the structure. The spores mature and blow away to start the process over again.
The slime mold does no harm to plants. It only helps decompose (compost) the organic mulch. They require moisture to develop and to move around. We see them here in New Mexico during moist periods or highly irrigated locations.
We seek to improve the lives of New Mexicans, the nation, and the world through research, teaching, and extension.
Barry LeBlanc’s shady garden at 301 Duclos St. is the winner of the Lafayette Garden Club’s Garden of the Month award for October 2015. A multitude of shade-loving plants brighten the garden including variegated Aztec grass, hydrangeas, baby ferns, hostas, mock orange, cast iron plants, sasanquas, gardenias, elephant ears, geraniums, ligularia and impatiens. (Photo: Submitted)
QUESTION: Recently I planted a camellia between two pecan trees. Someone has since told me that the camellia will not grow there, that there is some kind of poison released by the pecans that would damage the camellia. Should I move it?
ANSWER: Can you picture the ground under most pecan trees? The ground will be covered with leaves and bare of other plants. The leaves contain an acid which will enter the soil when the leaves decompose. This acid doesn’t hurt the pecan tree, but discourages or kills certain other plants growing near it.
This is a process called allelopathy by which a plant releases chemicals that can either inhibit or benefit other plants. Since most allelopathic plants cause harm to certain other plants — for example, the pecan to the camellia — you may want to move your camellia somewhere else,
Allelopathic substances can work like herbicides, preventing the germination and growth of the seedlings of competing species. Plants that are under stress, such as those with pests, diseases, or less than optimum access to nutrients, sun, or moisture, are at an even higher risk for being eliminated by allelopaths.
Depending on the plant, allelopathic substances can be released from a plant’s flowers, leaves, leaf debris and leaf mulch, stems, bark, roots, or soil surrounding the roots. Some of the chemicals biodegrade over time while others can be persistent in the soil.
Probably the best-known of the harmful allelopathic plants is black walnut (Juglans nigra). All parts of the tree — roots, bark, leaves, nuts, and even rainwater that falls off a leaf — release an allelopathic substance called juglone. Pecan is also a notorious offender, especially near azaleas and camellias.
Other common trees with harmful allelopathic properties include eucalyptus, sugar maple, tree-of-heaven, hackberry, southern wax myrtle, American sycamore, cottonwood, black cherry, red oak, black locust, sassafras, and American elm.
So what can you grow near your pecan and black walnut trees? Try serviceberry (Amelanchier), shasta daisy (Leucanthemum x superbum), speedwell (Veronica sp.), or American arborvitae (Thuja occidentalis), or better yet, go to the Internet to find a full list of trees, shrubs, vines and flowers that are not affected by allelopathic substances.
Q: I have spider lilies (red and gold) long ago planted in my garden which is now in complete shade. If possible and/or when can I transplant them to a more dappled shaded area and how many years before they begin to bloom again?
A: Yes, you can transplant them, but because they are finicky, they may fail to bloom two or more seasons afterwards. This will apply to any time they are disturbed. The best time to transplant is when the foliage begins to die back in late spring or early summer.
Lycoris bulbs provide an enormously entertaining show for the gardener, popping up out of nowhere to showcase their incredible blossoms on bare stems in late summer and early fall, disappearing only to return as rich green foliage in late fall and winter, then retiring to dormancy in late spring and early summer.
Plant them in soil enriched with organic materials such as leaf mold and treat them to an application of bulb fertilizer immediately after flowering.
Q: I have a friend that moved here from Mississippi and is planning her yard here in Lafayette. What books for our area would you recommend?
A: We are fortunate that there are several good gardening books written specifically for the Gulf Coast region available at local book stores, just be sure that they are for the Gulf Coast region and not for California or New England.
For landscaping and planting a yard in Lafayette, I’m going to recommend my book, “Blooming Trees and Shrubs of the Coastal South,” which is available at most local plant nurseries or at Amazon.com. Its theme is based on planting trees and shrubs that will provide several sources of seasonal blooming color every month of the year and it is illustrated with color photographs taken by local gardener/photographers.
Another favorite, which most bookstores will order for you, is “Houston Garden Book: A complete guide to Gardening in Houston and the Gulf Coast” (0-940672-55-3). This book has excellent information on gardening in general as well as in the compatible Houston area, along with beautiful photographs of local plants and landscaping.
The Lafayette Parish Master Gardeners’ Fall Plant Swap will be held today at the Demonstration Beds at the Ira Nelson Horticulture Center. Sign-in will begin at 9 a.m. and the formal swap will start at 9:30 a.m.
Participants must bring one plant for the formal swap and as many others as they wish to trade informally before and after. Plants that don’t find a home will be donated to Habitat for Humanity. Donations of foundation plants or shrubs will be accepted for the Habitat for Humanity bin. Swappers have been looking for red crocosmia, yesterday today and tomorrow, Louisiana irises, heirloom roses and many other plants.
Fall Series continues
All Seasons Nursery and Landscaping, 2974 Johnston St., is presenting the topic Gardening in Limited Spaces at a Know to Grow seminar today. The free seminars are held on Saturdays at 10 a.m. unless otherwise noted.
Looking ahead, the topic to be presented Oct. 10 will be Fall and Winter Vegetable Gardening (How, what and why, plus benefits). For information call 337-264-1418.
Felder Rushing to speak at Master Gardener meeting
The Lafayette Parish Master Gardener Association will meet Oct. 14 to hear garden writer and lecturer Felder Rushing speak on the topic Slow Gardening — Cajun Style, defined as gardening with all senses, all seasons and savoring it all.
Rushing, author of several popular gardening books, publishes syndicated news columns, hosts a weekly MPB radio show and contributes hundreds of articles and photographs in regional and national gardening magazines.
To rid the tree of this aphid infestation, you will need to do the following:
Get some trickle or another sticky tape-like product that can be wrapped around the base of the tree. Make sure that it is wrapped tightly, as you do not want to have a situation where the ants can crawl up underneath it. The material that you use should be relatively weather-proof and it should be able to last for a couple of weeks. This should prevent the ants from being able to carry more aphids up into the tree.
Now that you’ve taken away the ants ability to restock their aphid farm, you should hose down the leaves of the tree. The goal here is to git rid of the aphids that are currently feeding on the tree. Be sure to spend a few minutes at this, just to make sure that you’ve reduced the vast majority of them. Leftover aphids will die off pretty quickly, especially seeing as their bodyguards can no longer climb up to protect them. It is also worth noting that an aphid only has a lifespan of about 20-40 days.
As an additional measure against the aphid infestation, you can place ant killer at the base of the tree (in many cases, this is where the ant nest is located). If you’re against the notion of killing ants, then you can use a natural repellent such as mint tea (grind the leaves up and sprinkle them at the base of the tree).
That’s it. If you follow the above steps, the infestation will be gone and that horrible sticky residue will no longer drip from the leaves of the tree. Typically – This will solve the issue until the sticky tape around the tree dries out and the ants start to return.