56°F
weather icon Clear

Control whiteflies as soon as you see them

Q: This past year our pomegranate bush had a lot of whiteflies. I know they do damage to the bush and so I want to control them organically and naturally. How would you suggest doing that?

A: Whiteflies are a bad insect problem for any plant. I would rank them with the hard-to-control list of insects. In small numbers, they can be tolerated, but their populations grow so quickly that small numbers lead to large numbers very fast. For that reason, it’s important to get them under control early, as soon as you see them, in late spring and early summer. Don’t wait.

Damage is associated with their feeding. Their feeding supports a quick growth in their population as summer temperatures get hotter. They love the heat, and they’re not seen around much until June or July. Once you see them and it’s hot, watch out. You are behind the curve and they are way ahead of you.

Control is two-pronged. First, spray pomegranate bushes on a warm day in December and then again in January with a dormant oil. You can use the commercial brands of dormant oils and horticultural oils, or you can use soybean oil, canola oil, rosemary oil or cinnamon oil.

Spray all of the branches after pruning top to bottom, and spray a little extra shot at the base of each tree. This spray suffocates insects that might be hiding out during the winter months. It is the most important spray for controlling insects that will be problems in 2020.

In late May, start weekly inspections of the leaf undersides for whitefly adults. The adults look like living dandruff. You probably won’t see the eggs or immature forms because they are so small, but you will see the adult females preparing to lay eggs or protecting their young so that they can build their populations as quickly as possible.

Pull these leaves off when you see them infested and dispose of them or vacuum them. This practice slows their populations way down.

At the beginning of June, hang bright yellow or bright blue thick construction paper in the tree smeared with Vaseline. Whiteflies fly toward bright yellow and bright blue objects, and the Vaseline causes them to get stuck. As these traps start to fill, replace them with new ones. It might look a little funny, but light reflected from aluminum foil repels them.

If populations are totally out of control, spray with an insecticide to get their populations back under control. As a homeowner, use pesticides when all other attempts fail. Spraying with insecticides, however, have other consequences and should be a last resort.

Q: Our gardener thought a worm of some kind was causing damage to some of our 8-year-old bushes in our backyard. A few of them are OK, and a few have yellowed with dead branches at the tops. I bought some Bioadvanced Tree and Shrub liquid to protect them but want your advice before I apply it.

A: Judging from the pictures you sent and small red fruit still hanging on the bushes, they look like pyracantha, aka firethorn. I am 99 percent sure the dieback you mention is from borers earlier in the year. Pyracantha damaged by intense sunlight attracts borers, particularly if they are pruned incorrectly and planted in very hot locations. I will get to the chemical you bought in just a second.

The yellow leaf color can happen for many reasons, but in this case, it is an early sign of dieback from borer damage. Yellow limbs turn brown nearly overnight during the heat of the summer.

Pyracantha shrubs generally do well in our desert climate, but avoid planting them in extremely hot locations in the yard. They don’t like to be surrounded by rock. Planting them in desert landscapes surrounded by rock is not a good thing. If your shrubs are treated this way, they will continue to die over the next few years, faster if they are pruned incorrectly.

Pyracantha grows best on the north and west sides of buildings. These locations provide relief from the hot sun in late afternoons. They grow well when planted in soils amended with rich compost or a planting mix with added fertilizer.

After planting, either cover the soil surrounding them in wood chips or use rock large enough so that compost can be sprinkled and washed through them with a hose every one to two years. Covering the soil with rock and not adding compost to it exhausts any organics in the soil. Plants surrounded by rock start to suffer after three to five years.

I rail against the use of hedge shears in landscapes, but in this case, pruning with hedge shears is a faster option. Pruning with hedge shears will encourage thick, shady growth and protect larger branches from sun damage. Otherwise, hedge shears are a no-no unless pruning a hedge.

You got the right chemical to apply because it contains imidacloprid. Don’t apply it in December but wait until after the pyracantha flowers in late spring. After the pyracantha finishes flowering the spring, apply this chemical as a soil drench soon after flowers are gone.

Q: Can you recommend a good drip irrigation valve to use? I currently have Irritrol 205 valves and replacement parts are readily available, but I’m wondering if it would make more sense to just replace them with a newer product?

A: Years ago, irrigation valves might or might not work with drip irrigation because of the low operating pressure and the sometimes small amount of water that flowed through it. Not anymore. Most irrigation valves can be used for drip irrigation now. The irrigation industry doesn’t want to lose out.

The Irritrol 205 series of valves are workhorses, and unless the body is cracked, I would keep it. Replacement parts are easy to get, and it operates at low pressure and can handle very low amounts of flowing water. It is a reliable and inexpensive valve for drip irrigation.

Make sure you match the drip irrigation equipment you’re using with an appropriate pressure regulator and use a 150-mesh filter. Always flush your drip irrigation system on a regular basis, usually monthly if it’s clean water, and every time it is repaired.

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.
Local Videos
Mike Hansen and Cecilia Hansen
Mike Hansen and Cecilia “Cecy” Hansen discuss their journey of fostering to adoption. (Elizabeth Page Brumley/Las Vegas Review-Journal)
Las Vegas jury convicts man in woman’s 2018 rape, murder
On Friday a Las Vegas jury convicted 52-year-old Charles Talley Jr. of first-degree murder and sexual assault in the rape and killing of Kelly Deanne Kazoon inside an east valley apartment.
Las Vegas slogans and ad campaigns through the decades
Take a trip through decades of Las Vegas ad campaigns as the new slogan will be unveiled during the Grammys on Sunday. (Renee Summerour/Las Vegas Review-Journal)
Teaching about the Holocaust
Teacher Mitchell Kalin and former students discuss the power of empathy and compassion. (John Przybys/Las Vegas Review-Journal)
Metro Captain Sasha Larkin
Captain Sasha Larkin provides some updates about what is happening in Northwest Area Command in this 2019 video. (Metropolitan Police Department)
The Las Vegas Raiders give back - VIDEO
The Raiders are not even in Las Vegas yet but are already making a big impact on the community, giving out hundreds of hygiene kits to local vets and pledging $500,000 to eliminate school lunch debt in Nevada. (Le'Andre Fox and Renee Summerour/Las Vegas Review-Journal)
1 person dies in three-vehicle crash in south Las Vegas - VIDEO
Las Vegas Boulevard South reopened Wednesday morning, nearly seven hours after a three-vehicle crash left one driver dead and another seriously injured, according to police. (Bizuayehu Tesfaye/Las Vegas Review-Journal) @bizutesfaye
1 person killed in south Las Vegas Valley crash - VIDEO
One person was killed and another was injured in a three-vehicle crash on Las Vegas Boulevard South near East Warm Springs Road, Wednesday, Jan. 22, 2020. (Glenn Puit/Las Vegas Review-Journal)
Shooting at Las Vegas Fashion Show mall injures 3 - VIDEO
Three people were injured Tuesday night, Jan. 21, 2020, in a shooting at Fashion Show mall. (Las Vegas Review-Journal)
Touro University Nevada student says demonstration saved her life - VIDEO
Student Erica Stiles describes how her cancer was found during a classroom demonstration. (Mary Hynes/Las Vegas Review-Journal)
Scouts BSA troop takes part in day of service - VIDEO
Members of Las Vegas Troop 155 with Scouts BSA painted a fence and picked up trash as part of a day of service at Spring Mountain Ranch State Park west of Las Vegas on Monday Jan. 20, 2020. (Elizabeth Page Brumley /Las Vegas Review-Journal) @elipagephoto
Incident with 'suspicious device' resolved - VIDEO
Lt. Zachary Burns of the Las Vegas police department's armor section gives an update on the suspicious device found at a Saver's store in the 2300 block of East Tropicana Avenue on Monday, Jan. 20, 2020. (Glenn Puit/Las Vegas Review-Journal)
Elderly woman robbed in Fremont elevator - VIDEO
An elderly woman was robbed in an elevator on the 300 block of Fremont Street. Video courtesy of Las Vegas Metropolitan Police Department. (James Schaeffer/Las Vegas Review-Journal)
Martin Luther King Jr. associate speaks to Las Vegas students - VIDEO
Robert Green, 86, a Las Vegas resident and close confidante of Martin Luther King Jr., talks to students at Matt Kelly Elementary School in Las Vegas. (Las Vegas Review-Journal)
Helicopter pilot continues long recovery after Grand Canyon crash - VIDEO
Scott Booth, a former pilot for Papillon Grand Canyon Helicopters, talks about piloting a Papillon tour helicopter when the aircraft crashed in Grand Canyon in 2018, killing five of the six passengers. (Erik Verduzco/Las Vegas Review-Journal)
Annual eagle survey at Lake Mead and Lake Mohave - VIDEO
The National Park Service gets out on the waters of Lake Mead and Lake Mohave each year to count any raptors they lay eyes on. The birds are at the top of a food chain, so monitoring their numbers over time can help indicate if problems are occurring with the environment and the rest of the chain below them. (Ellen Schmidt/Las Vegas Review-Journal)
Wrong-way driver causes fatal crash near Las Vegas airport, authorities say - VIDEO
A suspected impaired motorist driving the wrong way on the Airport Connector caused a crash that killed another driver near McCarran International Airport early Friday morning, Jan. 17, 2020, according to law enforcement. (Glenn Puit/Las Vegas Review-Journal)
Las Vegas police give details on officer-involved shooting - VIDEO
Las Vegas police identified the officer and show body cam video of the officer who discharged his weapon at a suspect accused of shooting his mother at a credit union, Friday, Jan. 17, 2020. (Renee Summerout/Las Vegas Review-Journal)
1 person killed in wrong-way crash near Las Vegas airport - VIDEO
A wrong-way driver struck another vehicle, killing that driver, on the Airport Connector near McCarran International Airport early Friday, Jan. 17, 2020. (Glenn Puit/Las Vegas Review-Journal)
Sombrero wearing pigeons found - VIDEO
Sombrero wearing pigeons found in Reno by City Manager Sabra Newby during a ride-along with parking enforcement. (Renee Summerour/Las Vegas Review-Journal)
Alpine fire first responders recognized
MedicWest paramedic Miranda Smith describes the the scene when first responders arrived at the Alpine Motel Apartments fire.
The car that Tupac was shot in is for sale - VIDEO
The vehicle that legendary rapper Tupac Shakur was riding in when he was shot after a boxing match in Las Vegas is up for auction. The black 1996 BMW 7 Series is listed by Celebrity Cars Las Vegas for $1.75 million. (Angus Kelly/Las Vegas Review-Journal)
SUV crashes into art piece at Eastern and 215 Beltway - VIDEO
Artwork of a giant head was sent rolling when an SUV slammed into the artwork installed on a median at Eastern Avenue and the 215 Beltway in the southern Las Vegas Valley on Saturday morning, Jan. 11, 2020. (B.J. Calomay)
Alpine residents struggle to find new housing after fire - VIDEO
Many residents displaced by the Alpine Motel Apartments fire in downtown Las Vegas say they are struggling to find long-term solutions in a region where affordable housing is in short supply. (Michael Quine/Las Vegas Review-Journal)
Biden meets with Vegas Latino community - VIDEO
Presidential candidate Joe Biden met with members of the Latino community at Rancho High School. (James Schaeffer / Las Vegas Review-Journal)
Margaret Rudin's first interview after release from prison
Convicted killer Margaret Rudin maintains her innocence in her first interview after spending 20 years in a Las Vegas prison for the murder of her husband, Ron Rudin.
Locals cheer on James Holzhauer at 'Jeopardy!' watch party - VIDEO
Imitation is the sincerest form of flattery. But James Holzhauer would have a better chance at winning “Jeopardy! The Greatest of All Time” tournament if Ken Jennings would stop copying his aggressive betting strategy. (James Schaeffer / Las Vegas Review-Journal)
Henderson, other Nevada cities consent to refugee resettlement - VIDEO
Henderson will continue to welcome refugees for resettlement, according to a December letter from Mayor Debra March. (James Schaeffer / Las Vegas Review-Journal)
Ceremony held for Elvis artist Trent Carlini - VIDEO
A ceremony was held for Elvis impersonator Trent Carlini on Wednesday night at The Space in Las Vegas. (James Schaeffer / Las Vegas Review-Journal)
Las Vegas bus attack caught on video
Video released Metro shows two men talking on a bus on Dec. 13, 2019. A few seconds into the video, the younger man stands up and punches the older man in the face. (Las Vegas Metropolitan Police Department)
Fire at Bella Vite Apartments in central Las Vegas - VIDEO
No one was injured in a fire at Bella Vita Apartments, near West Flamingo Road and South Decatur Boulevard, early Wednesday, Jan. 8, 2020. (Glenn Puit/Las Vegas Review-Journal)
North Las Vegas police release details of first fatal officer-involved shooting of 2020 - VIDEO
North Las Vegas Police Chief Pamela Ojeda discusses details of the departments first fatal officer-involved shooting for 2020. (Michael Quine/Las Vegas Review-Journal)
Fremont Street is getting a new LED sign - VIDEO
The Fremont Street Experience is planning to add an LED sign that pays tribute to downtown Las Vegas’ history. The 430-square-foot sign is set to be built on the east side of Main Street and Fremont Street. (Las Vegas Review-Journal)
Ethel M Chocolates cactus garden lit for Christmas - Video
The 26th Annual Ethel M Chocolates Cactus Garden Lighting in Henderson, Tuesday, Nov. 5, 2019. The garden will be open until 10 p.m. daily through the holidays. (Rachel Aston/Las Vegas Review-Journal) @rookie__rae
Therapy dogs dress up for Halloween at Poets Walk Henderson - Video
Therapy dogs dress up for a Halloween costume contest at the Poet's Walk Henderson Memory Care facility. (Nathan Asselin/Las Vegas Review-Journal)
THE LATEST
Verticillium wilt cause death of single branch

Verticillium wilt disease plugs the internal tubes that carry water from a tree’s roots to the leaves. It commonly infects a single branch, causing it to die and appear like it is not getting enough water.

Citrus plants have different tolerances to winter cold

There are two strikes against citrus growing well in the Mojave Desert. The first is their variable tolerance to freezing temperatures during the winter. The second strike is that oftentimes citrus trees flower in early spring when very light freezing temperatures are possible. Tolerance to these freezing temperatures is practically nil.

Cutting tree roots always damages the tree

You can typically remove about one-third of the total tree roots with no problem. This is done sometimes when trenches are cut in the soil for burying irrigation lines. But when roots are cut, about one-third of the top should be removed as well.

Deep watering stakes not necessarily needed for new tree

The annual South Valley Rose Show will be held Nov. 9 at the University of Nevada Cooperative Extension offices on the corner of Windmill Lane and Paradise Road. Rosarians will be present to answer questions about growing roses in our hot desert climate and poor soils from 1 to 4 p.m.