weather icon Mostly Cloudy

While unsightly, slime flux is nonlethal tree disease

Q: I have two paloverde trees in front of my house. One seems to be fine while the other has struggled for four years. I am told the tree is healthy, but every summer it leaks white, sticky foam from the trunk. This foam attracts bees and beetles. The tree has received professional borer treatments twice a year, but it’s still bad.

A: Save your money. This is not an insect problem. It is a disease problem, but a disease that will not kill the tree. Let me explain.

You mentioned bees and beetles are attracted to this foam. I am 99 percent sure, based on the picture you sent and your description, this is a disease called slime flux, sometimes called bacterial wetwood. It is a nonlethal disease to the tree. It attacks only dead or dying wood inside the core of the tree.

Nonliving wood inside the tree cannot fight off disease microorganisms because it is dead. The only microorganisms which feed on this wood are saprophytes. Similar microorganisms feed in compost piles and convert raw waste into compost.

These microorganisms do not feed on living parts of the tree because living parts of healthy trees can fight back. Bacteria involved with slime flux create a foam with a characteristic smell of fermenting yeast or brewing beer. This yeasty smell attracts flies, bees and other insects such as beetles because this smell resembles rotting or fermenting fruit.

Normally, this disease bothers us because of these insects and its general ugliness. It does not hurt the tree. It may bother us because the foam dripping down the trunk of the tree causes discoloration of the trunk and unsightliness.

Probably this infection was transferred to this tree by unsanitary pruning practices. I always emphasize sanitizing and sharpening pruning equipment. When a tree is infected with a disease, it is extremely important to sanitize the pruning equipment before pruning a new tree. There is no cure for this problem. You and the tree must live with it.

Some arborists may drill a hole into the tree trunk and insert a metal tube just below the foam and sticks out of the trunk. This foam drains inside the tube and drips to the ground without touching the trunk. Make sure any tools and equipment that touch the inside of the tree have been sanitized thoroughly.

Q: I’ve read somewhere that you should not place black plastic under rock used for desert landscaping. I have it there. We are an older couple and cannot remove it easily. Can we do anything else?

A: Using plastic under rock mulch in desert landscapes prevents air from reaching the roots. Roots need water, but they also need to breathe. Black plastic is not permanent while rock is. Sooner or later, this black plastic will begin poking through the rock mulch as it is punctured and disintegrates.

Consider punching air holes through the plastic at the base of trees and other plants to help air reach the roots. The downside of this recommendation is it may cause the black plastic to rip and disintegrates sooner, peaking its ugly head through the rock.

Don’t think you have to remove all this plastic at once. If you see some sticking up through the rocks, remove it until more appears.

A more expensive option instead of plastic is called a weed barrier. This is spun or woven material that breathes, allowing air and water movement.

I personally don’t particularly like weed barriers because they do not prevent many of our most troubling weeds like common Bermuda grass and nutgrass. Instead, I would recommend spending a little bit more money on rock mulch and applying it thicker, perhaps 3 to 4 inches deep instead of 2 inches.

Q: I see you mention a specific iron product every year, but I decided to buy it for use early next spring. We prefer to buy it online. When I searched for it, about 80 choices appeared and now I am confused.

A: Not many places stock this iron fertilizer locally. Helena Chemical and Viragrow are the only places I know locally that carry it. When buying it online, use the keywords “iron,” “fertilizer” and “EDDHA.”

I have been waiting for an excuse to explain this iron dilemma more thoroughly. Using the wrong iron product when the chemistry of the soil or water is not right, results in a waste of time and money.

The chemistry of our desert soils is responsible for most yellowing seen in plant leaves. You are right, there is a huge variety of iron products available. Which one to use? The problem is not with the product. The problem is matching the product to our soils because of their chemistry.

There are two methods for applying iron to yellow plants: a single application to the soil in early spring or three to four applications of an iron spray directed toward yellowing leaves later in the season.

A single iron fertilizer application to the soil makes green leaves continuously as the plant grows through the year. Multiple sprays of iron to the leaves is the only method that corrects leaves already yellow. Each spray, a few days to a week apart, makes the leaves darker and darker.

All iron fertilizers work if the soil pH (which is related to its alkalinity) is 7.5 or lower. If an iron product is applied to the soil and expected to work, the soil pH must be 7.5 or lower. If an iron product is mixed with water and sprayed on the leaves, the pH of the water must be 7.5 or lower.

The magic number to remember is 7.5. Most desert soils and our water supplies are closer to 8. This becomes a problem for all iron products except one.

Iron fertilizers that contain the chelate EDDHA are 100 percent effective with any amount of alkalinity. That’s right, any amount. But the chelate in the ingredients must be EDDHA.

When applying iron fertilizer to soils in early spring, just before new growth appears, use an iron fertilizer containing the chelate EDDHA. It will tell you so in the ingredients.

Later in the growing season when leaves begin yellowing, all iron fertilizers sprayed on the leaves work if the pH of the water is below 7.5. Use distilled water or water from reverse osmosis. This water has little alkalinity and a pH of 7.

It’s difficult to get iron sprays inside the leaves. Leaves have no roots, so we must improve the movement of this iron spray inside the leaf. This is done by “making the water wetter.” Adding a liquid detergent to the spray at the very end of mixing helps the movement of the iron inside the leaf.

Q: I’m not sure if the branch at the bottom of my lemon is a sucker or a real branch. I know if it comes from below the graft to remove it, but I can’t see where it comes from exactly. The leaves from this growth are huge, too. It’s about 6 to 8 inches from the soil.

A: Look for long thorns. The rootstock used for citrus in our climate is usually sour orange, which produces an extremely sour, nonedible citrus fruit. It has huge thorns, up to 2 inches long.

If this growth does not have thorns, or if they are small, it is probably lemon. The sucker is right on the edge, but I think it is coming from the scion (lemon).

If you apply compost to the tree as it is growing, it may make some huge leaves. If you use compost as a fertilizer, apply it each year after you harvest the fruit. Water it in thoroughly.

If you applied woodchips to the soil beneath the tree, apply it in a larger area under the tree as the tree gets bigger. Apply enough so it is at least 4 inches deep. Keep woodchips 6 inches from the trunk or it can rot it.

Bob Morris is a horticulture expert and professor emeritus of the University of Nevada, Las Vegas. Visit his blog at xtremehorticulture.blogspot.com. Send questions to Extremehort@aol.com.

Don't miss the big stories. Like us on Facebook.
Entertainment Videos
Heavier traffic expected from EDC festival attendees
Electric Daisy Carnival attendees began to vacate the Las Vegas Motor Speedway starting before 5 a.m., the majority heading south on Interstate 15.
What it's like to skip the lines and fly by helicopter to EDC
What it's like to skip the lines and fly by helicopter to EDC. (Janna Karel Las Vegas Review-Journal)
DJ Steve Aoki visits Las Vegas comic book store
DJ Steve Aoki visits Torpedo Comics in Las Vegas Friday, May 17, 2019, for a signing for his new comic book series "Neon Future." (K.M. Cannon/Las Vegas Review-Journal) @KMCannonPhoto
Las Vegas Smith & Wollensky opens at The Venetian
After 18 years, the Smith & Wollensky location on Las Vegas’ south Strip closed in 2017, to be re-born two years later with a rib-cutting — instead of a ribbon-cutting — in The Grand Canal Shoppes at The Venetian. (Heidi Knapp Rinella/Review-Journal)
Colin Cantwell, Creator Of Iconic Star Wars Ships Visits Vegas
Colin Cantwell, who created and designed such "Star Wars" ships as the X-Wing fighter, and Death Star, met fans at Rogue Toys in Las Vegas today. (Mat Luschek / Review-Journal)
Beauty & Essex in Las Vegas makes an EDC Wonder Wheel
In honor of the Electric Daisy Carnival, Beauty & Essex at The Cosmopolitan of Las Vegas makes its Wonder Wheel party-worthy. (Heidi Knapp Rinella/Las Vegas Review-Journal)
Giada talks Vegas Uncork’d
Giada De Laurentiis talks during Aperitivo Hour, a Vegas Uncork'd event, at her Caesars Palace restaurant, Pronto, May 10, 2019. (Al Mancini/Las Vegas Review-Journal)
Scenes from Vegas Uncork’d 2019 on the Las Vegas Strip
The 13th edition of Vegas Uncork’d by Bon Appetit brought four days of food, wine, celebrity chefs and parties to town, May 9-12. (Heidi Knapp Rinella/Las Vegas Review-Journal)
Three ingredients Gordon Ramsay can’t live without
Bon Appetit's Andy Baraghani interviews the "Hell's Kitchen" chef during a Vegas Uncork'd event at Caesars Palace, May 11, 2019. (Al Mancini/Las Vegas Review-Journal)
Vegas Uncork’d launches wiith bubbles and a blade
Dozens of chefs representing some of the Strip’s top restaurants gathered Thursday at The Cosmopolitan of Las Vegas to launch the 2019 edition of Vegas Uncork’d by Bon Appetit. (Al Mancini/Las Vegas Review-Journal)
Bunky the Clown at the clown convention
Bob "Bunky the Clown" Gretton talks about his life as a clown and the Clown Convention which was in Las Vegas at Texas Station this week. (Mat Luschek / Review-Journal)
Frying soft-shell crab at Lola’s in Las Vegas
At Lola’s: A Louisiana Kitchen in Las Vegas, soft-shell crab is breaded and fried and served either as an appetizer, po’boy or platter. Heidi Knapp Rinella/Review-Journal
The Stove in Henderson makes Pecan Pie Pancakes
At The Stove in Henderson, chef/partner Antonio Nunez stacks buttermilk pancakes with pecans and dulce de leche and tops them pie crust crumbs. (Heidi Knapp Rinella/Las Vegas Review-Journal)
Vinnie Paul remembered at Count's Vamp'd
The late rocker's favorite table at one of his favorite clubs in Las Vegas. (Jason Bracelin/Las Vegas Review-Journal)
4DX movie experience at Red Rock
4DX movie experience during a demo reel at Red Rock. (Christopher Lawrence/Las Vegas Review-Journal)
What To Do On May The 4th
There are plenty of events going on May the 4th this year around Las Vegas. Celebrate Star Wars and Comic Book Day all at once. The Rogue Toys, the 501st, Rebel Legion and Millennium Fandom Bar are all hosting fun events to help celebrate your geek-dom. (Mat Luschek / Review-Journal)
Las Vegas Water Sports Introduces New Attraction At Lake Las Vegas
Las Vegas Water Sports will debut its new aqua park attraction at Lake Las Vegas Days this weekend. (Mat Luschek / Review-Journal)
Making the Space Invader at Greene St. Kitchen in Las Vegas
Lysa Huerta, pastry cook at Greene St. Kitchen at the Palms in Las Vegas, starts with angel food cake, Fruity Pebbles ice cream and strawberry sorbet to create a space creature engulfed in flashing lights and swirling mists. (Heidi Knapp Rinella/Las Vegas Review-Journal)
Las Vegas Pools
The M, Park MGM and NoMad are just a few great pools in Las Vegas. (Mat Luschek/Las Vegas Review-Journal)
Jose Andres explains Iberico pork
(Al Mancini/Las Vega Review-Journal)
Inside Life is Beautiful
Craig Asher Nyman explains how Life is Beautiful festival is booked and talks about this year's line-up. (Jason Bracelin/Las Vegas Review-Journal)
Tattoo'd America Pops Up In Vegas
Tattoo'd America, a new pop-up attraction on the Linq Promenade, had their grand opening Friday. The attraction is dedicate to the culture of tattoos. (Mat Luschek / Review-Journal)
Jose Andres gets key to the Strip
Chef Jose Andres was presented with a Key to the Las Vegas Strip and a proclamation declaring April 26 Jose Andres Day in Clark County by County Commissioner Tick Segerblom on Friday. The ceremony took place at his restaurant Bazaar Meat in the SLS Las Vegas. (Al Mancini/Las Vegas Review-Journal)
Sadelle’s in Las Vegas makes a grilled cheese with an inverted bagel
Michael Vargas, executive sous chef at Sadelle’s at Bellagio in Las Vegas, inverts an everything bagel and grills it with Swiss, cheddar and Muenster cheeses to make the Inverted Bagel Grilled Cheese. (Heidi Knapp Rinella/Las Vegas Review-Journal)
Learn how to make China Poblano's Salt Air Margarita
Learn how to make China Poblano's Salt Air Margarita (Janna Karel Las Vegas Review-Journal)
Tattoo'd America invites you to have fun and take pictures
Kassandra Lopez at Tattoo'd America invites you to have fun and take pictures. (Janna Karel/Las Vegas Review-Journal)
Prime rib is carved tableside at Lawry’s The Prime Rib in Las Vegas
Dave Simmons, executive chef of Lawry’s The Prime in Las Vegas, which plans special cuts for National Prime Rib Day, demonstrates the restaurant’s service from rolling tableside carving carts. (Heidi Knapp Rinella/Las Vegas Review-Journal)
Making gluten-free pizza at Good Pie in Las Vegas
Good Pie owner/pizzaiola Vincent Rotolo makes his gluten-free pizza.
Rockabilly fans enjoy Las Vegas weather poolside
Viva Las Vegas Rockabilly Weekender runs Thursday, April 18th through Sunday, April 21st with a huge car show on Saturday featuring The Reverend Horton Heat, The Delta Bombers and The Coasters. (Michael Quine/Las Vegas Review-Journal)
Brownie sundae at VegeNation in Las Vegas is completely vegan
Donald Lemperle, chef/owner of VegeNation in Las Vegas and nearby Henderson, NV, makes his sundae with ice cream made with coconut and almond milks, a brownie made with coconut flour and oil and organic sugar and cacao, and fresh fruit. (Heidi Knapp Rinella/Las Vegas Review-Journal)
Spray grapevines to control pests

Grapeleaf skeletonizer and grape flea beetle were found in the orchard during the last couple of days. These two pests damage grape leaves but few other plants.

Removing dead fronds doesn’t affect health of sago

Q: The top ring of sago palmfronds died after I transplanted it but remain on the plant. I left this brown ring of fronds around the crown of the plant and it looks like new growth coming from the center is OK. Should I trim off the dead fronds without disturbing the crown or just let them fall off?

Yellow leaves not necessarily caused by fertilizer

Q: I see many times where you’ve said fruit trees only need feeding in the spring. However, without periodic applications of nitrogen, my 3-year-old peach tree leaves become yellow. Could there something going on I should investigate?

Waxleaf privet should have more than one drip emitter

Q: I purchased a few waxleaf privet plants in February. They were planted in my yard using drip irrigation with one drip emitter per plant for about one month now. I am starting to see some black markings and yellowing on the leaves. I also think there may be some root rot, but I am unsure.

Removing excess fruit allows remaining fruit to grow larger

If you have fruit trees, the next big tree management activity you are facing is fruit thinning or removing excessive amounts of fruit so that the remaining fruit gets larger. Peaches, nectarines, plums, apples and pears must have excessive fruit removed if you want larger fruit. Do this as soon as the fruit reaches the size of your thumbnail.

Proper pruning, thinning, irrigation increases fruit size

Q: Peaches from my dwarf peach tree were very small again last year. This is the third year the fruit developed into a small size. We fertilize them twice a year with vegetable spikes and our in-ground system fertilizer system has Dr. Benson’s Natural Mix added five times per year. Any suggestions?

Grape varieties grown in hot dry climates do best here

Q: I am from San Miguel Community Garden, a nonprofit garden located near the North Las Vegas Airport. We are considering adding more grape plants to the garden. We have Flaming Red and Thompson grapes. You said you have grown many different varieties in the Las Vegas Valley, and I was wondering if you would share with me other varieties that were successful for you so we can explore them as well.