What causes rust spots on leaves?

As the season began earlier than normal, Tim Cahill was excited, but he kept waiting for things to change.

But the sun kept shining, the rain stayed away and he just continued shipping.

“All year I kept telling my wife, ‘This is just weird — something is not right,” says Cahill, owner of Cahill Family Greenhouses Inc. in Salem, Mo.

It was especially strange after last year, which proved to be one of the worst weather years for the industry between blistering heat in the South and nonstop rain in many other parts. But this year, Mother Nature seemed to be more sympathetic.

“If growers couldn’t grow in this year in our area, they really need to get out because the sunlight was so abundant in January, February and March – it was incredible,” says Scott Mason, general manager and grower at Ritter Greenhouse in Bridgeton, Mo. “It was some of the best weather growers have seen ever that they can remember.”

Cahill said he’s used to getting some rainy parts that provide a chance to catch his breath and catch up, but he didn’t see any of that this year.

“Usually in the spring you have a week or two where it does nothing but rain,” Cahill says. “We didn’t have any of that this year, so it was just perfect weather from start to stop.

“Last year, that’s all it did was rain. It was strange to go from last year, where you have that in your mind, to this year. All season it just seemed like there was something wrong — nothing was normal. It was one of those years where I said, ‘You’ll remember this year because they don’t happen very often.’ I kept watching the forecast and thinking, ‘OK, it will start,’ but it never did, which is nice.”

Nice indeed, as Cahill sold every plant he had and was empty by June 1.

“We’d sell whole plantings in two days,” he says. “In the normal time we’d sell one planting, I had three, almost four, plantings sold this spring compared to what would normally be, and I kept adding on every order.”

Yes, the spring season was a success, and some growers even saw double-digit sales increases over last year, which has provided hope for the future across the industry.

“For the most part, we’re past the worrying about will tomorrow come in terms of the recession and the effects we suffered through,” says Forrest Stegelin, associate professor of agriculture and applied economics at the University of Georgia.

Here’s a look at what went well this season and some of the concerns still on the horizon along with that hope.

Struggles despite successes
Despite a strong sales season, many people aren’t quite overjoyed yet. Stephanie Whitehouse is the sales and marketing manager for Peace Tree Farm in Kintnersville, Pa., and she says it wasn’t spectacular, but on a scale of one to 10, 10 being the best, she’d rate it a solid seven to eight, with last year being a five or six.

“It was definitely an improvement,” Whitehouse says. “I wouldn’t say it’s amazing or we’re jumping for joy here, but we’re content.”

Part of the hesitation to get excited comes from looking at the bottom line.

“It was one of the best selling years people have seen in the Midwest, but from a profitability standpoint, it was absolutely stagnant,” says Andy Krieger, co-owner of E. Krieger Greenhouses in Jefferson, Iowa. “A lot of volumes have gone out, but the profitability is really hurting in our industry right now.

“ good sales, and everybody is thinking, ‘This is wonderful,’ but when you look at the bottom line, it wasn’t there. There are double-digit sales increases, but then profitability is tighter and there’s no fat to draw from — no reserves after the last two or three years.”

He attributes part of that to: over-production, increasing costs, and a perceived less value because of big-box stores.

“Profitability is tight,” Krieger says. “Margins are tight because of fixed expenses, insurance, labor, fuel, right down the line. Fixed expenses and cost of goods have all gone up. The fat is gone. The reserves are gone.”

Whitehouse also agreed that the profitability levels aren’t higher despite increased sales.

“The fact that the winter was a lot more mild definitely helped lower the cost for heating,” she says. “But we found we were spending more on our biological control system.”

Since Peace Tree Farm is certified organic, it uses biological control for all of its pests.

“Because there wasn’t that cooling off season or that hard frost or normal winter temperatures, we were spending more time controlling for our insect population — successfully, but there was a longer control season than what we had seen in the past,” she says.

In addition to costs going up or having to spend more money in areas you may not normally need to, many growers may not see high profits this year because they’re spending money on maintenance or upgrades.

“I’m looking at upgrading some of the systems to try and stay competitive, so whether or not profits are up with where our priorities lie, that remains to be seen,” Mason says.

Profitability levels may also not be as high because many growers made much-needed adjustments to what they grew only to have wished they hadn’t. For Cahill, since 2008, his late plantings haven’t sold as well.

“I cut them back at least half this year, which I shouldn’t have, but how do you know?” he says.

Krieger also said that while the spring season started early, it also ended early.

“They bailed,” he says. “We were selling product in March and had a really good April, and after Mother’s Day, sales died off. Instead of looking for more, instead of them trying to garner some additional sales, I think the retail customers, at least our retail customers, just bailed. … Because the season was so early, it wasn’t extended. The window frame was exactly the same — it was just moved up a month earlier.”

Janet Peele is the owner of Aberdeen Florist & Garden Center in Aberdeen, N.C. There she grows 80 percent of what her garden center sells, but she saw her season start strong and fizzle out.

“We had really good early spring sales and a lot of interest,” she says. “It fell apart a little early this year — it wasn’t because of rain or hot days. I’m not sure if people are just holding back or what, but a lot of my landscape customers have cut back on them too, so I think there’s just a general tendency not to spend any money right now.”

As a result, she’s going to take a different look at what she grows for next year.

“I’m going to be much more careful,” Peele says. “I’m going to do some good analysis this year and decide what sold and what didn’t. … I’ve always gone about my planting with about a 10 percent expansion each year, knowing that something is going to fail and something will not come in seed-wise, but I’ll be a little more conservative next year.”

Peele says her customer base is more high-end but she’s also starting to see a growing military population in her area, so she thinks that as they start to learn about her center, it will increase business. But this new demographic will have different needs from her current one, so she’ll need to learn what they want — a common issue for many growers and garden centers alike. Krieger predicts more attrition in the industry as growers try to learn more about new ways of doing business.

“It’s going to take a while longer for the growers to really figure out what those new customers want — what the new dollar bill is looking for,” he says. “It’s going to take less growers and less product out in the marketplace and a more catered product line to meet the new customer’s needs.”

Trying new things
While many still have hesitations about the future, growers can’t deny that it was a good year at least, and it was a shift toward the future. Much of that has come from trying a variety of new things.

“Most of I was in touch with this spring … had a pretty positive outlook,” Stegelin says. “They admitted that they didn’t produce the sheer volume that they used to produce, but they became more aware of and the need to focus on basic business function rather than worrying about production. They’re all good at production and know how to produce, and it was a matter of running a business that they seemed to realize that there were some activities that they could be putting a closer tab on or at least directing their own personal efforts to.”

Stegelin says another way he’s been pushing change is by advising growers to raise prices, and he was excited that many did. They produced fewer plants — some by as much as 20 to 25 percent — but raised the prices and still saw their revenue come in about the same as in previous years.

He says another reason why many growers were successful this year was because they got away from the tried and true.

“The ones that felt they had a successful spring said they did something they hadn’t done in the past — took the initiative,” he says. “Instead of them growing it and waiting for it to come — kind of like the take off of “Field of Dreams” — that they had done in the past, they proceeded to do more outreach and pre-sale marketing efforts to communicate what their abilities were and find out what the needs were so that they could, in fact, make some last minute production changes rather than filling a greenhouse with plant material like they had in years past and assume they would sell it out the door.”

These changes weren’t out of desperation though, he says. Instead, it was a realization that they wanted to sell what they had and get the most money they could.

“A lot of people, in the past, would nickel and dime them in price, but when they took the initiative and instead of waiting for that buyer to show up on their doorstep, they trust the whole notion and put the buyers on the defensive in the sense that they were willing to accept the higher price — and without many questions asked,” Stegelin says.

Additionally, Stegelin says many growers are going more toward margin management now instead of sheer marketing and pricing. He says all the economists in the industry have been preaching this, but growers are starting to listen.

“Once we started talking essentially about margins and pointed out to them that every retailer around them is dealing with that as well as producers … they suddenly realized that was the way most businesses were operating, and the growers started looking at their own particular operation, and it shifted,” Stegelin says.

He says this year was also one that perhaps margins are probably not jumping a whole lot.

“They’re finding out that they’re probably not increasing their margins, but what they’re finding out is what their margins really are and what it’s going to take to get where they want ,” Stegelin says. “Some had unrealistic expectations for particular plant materials.”

He says some growers thought their pride-and-joy product was their best opportunity, but when they look at it closely, it may not be, or they can make changes to make it more economical for them. Or in some cases, it was better to instead focus more on differentiation and not offering the bread-and-butter products that a lot of retailers sell. Whitehouse says they decided to focus on more unusual plants this year that the company was already known for.

“The common annuals that a lot of other growers in our area are growing, we don’t need to be in that business and trying to compete with everyone else,” she says. “Our customers aren’t coming to us for those plants — they’re coming to us for the new, the unusual, the cool, the different plants that will help them set themselves apart as well.”

Cahill went the same way.

“I did more varieties but less of them,” he says. “I cut back on the staple products and added on more of the odd stuff, more of the newer stuff, just in smaller quantities. That helps me for ordering next year because I know what’s going to sell on the new stuff and what didn’t, instead of buying a bunch of it and getting hung with it.”

Whitehouse says that they also continued focusing on organic herb and vegetable programs.

“We did see another increase this year compared to last year and the year before that the edibles movement still is growing strong, and we still have a fairly big desire or there’s a lot of demand for that out in our market,” she says.

In addition to focusing on differentiating themselves, the Peace Tree Farm team also started an early season program this year and promoted it heavily. In the past, they offered a few plants available from the end of February through early April that are cold-hardy and have lots of color to get their garden center customers and the end-consumers excited about planting early. But this year, they expanded it to about a dozen plants, and they heavily advertised to their garden center customers, encouraging them to get their customers in early.

“I think took taking a look at how our spring season had gone last year and coming to the realization that the traditional spring season, from Easter to Memorial Day, is what it is,” Whitehouse says. “You can’t increase your sales that much because customers are locked into, ‘This is the traditional season.’”

She says people, no matter what, are going to be coming into the garden center and purchase plants, so they shifted focus to bringing people in and exciting the end-consumer earlier in the season and throughout the year. Doing this created some good buzz in their area and helped lead to a better year.

“Increasing your early spring sales is probably where you’re going to see most of your revenue coming in from,” Whitehouse says. “You’re going to see your most improvement throughout the season if you were to create an early spring program.”

Tales of pre-orders
A lot of the talk has been about garden centers not putting in as may pre-orders, and it’s been hard for growers.

Trey Pitsenberger is the owner of The Golden Gecko Garden Center in Garden Valley, Calif., and he didn’t put in pre-orders this year because he doesn’t have problems with availability.

“We have a problem here in California where we’ve always been able to snap our fingers,” he says. “We on the retail end need to work with growers more and make more assurances.”

Those assurances would certainly help many growers that depend on pre-orders. Last year Mason’s business had gotten to the point where they had about 40 percent of business in pre-orders, but this year it knocked down to about 25 percent.

“When we came to the table, it was price,” Mason says. “Price was the issue. Local customers went to out-of-state growers. How that’s possible, I have no clue.”

He also lost quite a bit of contract sales from a larger customer this year, so he shifted his focus in order to still be successful.

“We’ve transitioned into a filler,” Mason says. “As the plants went out the door so quickly for the IGCs, they didn’t have planned deliveries from larger growers, so smaller growers stepped in and carried that weight.”

He says that while many places are cutting down on variety, he increased the variety so that he wouldn’t miss out on sales opportunities.

“I wouldn’t cut down on variety,” Mason says. “Variety seemed to have made it for us. We only increased varieties this year. It seemed the more varieties we packed on, the more we were able to fill a truck with a single order to a single customer because we ended up being a one-stop shop. That really helped us this year. Besides the weather, the biggest contributing factor was adding varieties to our list and keeping customers well-informed.”

As a result, while he lost contract sales business, his revenue from the independent garden centers increased significantly for the first time in about five years.

“It was probably the best March we’ve ever seen as a company,” he says. “April kind of evened things out, but we had a strong late April. March definitely did it for us. … The IGCs were way up, and that really helped.”

Pitsenberger says that there are ways growers can work with garden centers for next year to avoid having to shift focus.

“Work with us earlier in the season,” he says. “Talk to us about what might be needed in the future. … more communication earlier in the season about what’s selling and the direction we can go and what can we do different that will set us apart from the supplies of our competition.”

While many said pre-orders were down, Peach Tree Farm saw a fairly large increase, thanks in part to a program offered by Hort Couture, which they serve as an allied wholesale grower for. Hort Couture offered a program last year at the end of the year where garden centers could pre-book for the spring with Peace Tree Farm and they would receive 10 percent of their total orders back as a credit toward POP and merchandising displays for promoting Hort Couture in their stores.

“That was a good, solid help to let us know early on that spring was probably going to be better than we had seen in the past,” Whitehouse says.

Whitehouse said they sold out of some materials early on, so some customers wished they had pre-booked.

“We said, ‘Hey, this is what happens when you don’t pre-book. We’re only going to grow a finite number of material, and when it’s gone, it’s gone,’” she says.

As a result, she anticipates more garden centers pre-booking this year.

“A lot of people are realizing that pre-booking is the way to go,” Whitehouse says. “I understand from a garden center standpoint it’s difficult to forecast what your season is going to be like, but if you can pre-book the items you know you’re going to need … that helps. Then as a garden center, you know you’ll have it and you can build your other orders around it.”

She said for those that had pre-ordered their Hort Couture products, many came back and added on other Peace Tree products to round out their orders.

Whitehouse says, “It definitely helped build really nice orders.”

The spring season proved to be a strong one for most growers because of implementing better business practices, finding ways to overcome down pre-orders, implementing new programs and differentiating from competitors. Because the weather is unlikely to be any better than it was this year, by continuing these initiatives and building on this year’s successes, next year can hopefully be even better.

Myrtle Combat

SERIES 30 | Episode 31

Jerry heads to Mt Coot-tha in Brisbane to find out how an invasive exotic fungus is threating an Australian plant with extinction, and what’s being done to save it.

Myrtle rust is a disease caused by the exotic fungus Austropuccinia psidii. And rust infects plants in the Myrtaceae family, including garden classics like Callistemon, tea trees and eucalyptus. About 350 native species have proven susceptible to myrtle rust, which causes deformed leaves, heavy defoliation of branches, reduced fertility, dieback, stunted growth, and eventual plant death.

Myrtle rust is spread by wind and humans with contaminated clothing, and it was first detected in 2010 in NSW. It has since spread rapidly and has established along the east coast of Australia from southern NSW to far north Queensland. It has also been detected in Victoria, Tasmania & the NT.

Dr Rod Fensham, Botanist from the Queensland Herbarium, is at the front line of the advance of myrtle rust and is blunt about its’ spread – “it’s proceeding well”. “It attacks Myrtaceae which is a massive family, but it isn’t indiscriminate – it seems to pick on certain tribes”.

One such plant being “picked ion” is the Native Guava (Rhodomyrtus psidioides). Rod says this plant was likely once very common in forest clearings in NSW and QLD, filling the niche that is now occupied by invasive lantana. It’s being “completely smashed” by myrtle rust and Rod says it’s “gone from being common to complete collapse”, and it’s now listed as critically endangered in NSW.

The sole remaining population in Brisbane is at Mt Coot-tha, and it is infected with myrtle rust with late Autumn and Winter being the prime time of year to see the tell-tale symptoms of the infection.

Generally, myrtle rust starts as small purple spots on leaves. Bright yellow spores form in pustules within these purple spots. Pustules fade to dull yellow and then grey as the infection ages. In severe infections, spots enlarge and merge, often causing leaf distortion. Myrtle rust attacks young, soft, actively growing leaves shoot tips and young stems, as well as fruits and flower parts of susceptible plants. “These plants still flower but don’t fruit”. Advanced infections may kill shoot tips and can eventually kill plants.

Myrtle rust spores can be spread easily via contaminated clothing, hair, skin and personal items, infected plant material, equipment as well as by insect/animal movement and wind dispersal. These characteristics make it extremely difficult to control and impossible to eradicate from natural settings once it’s already established. Home gardeners can help stop the spread of this pathogen by identifying the tell-tale signs of infection in susceptible plants in their garden. Infections manifest quickly, usually displaying in 14 days. Infected plants should be removed entirely, placed in a plastic bag and put in the bin, not green waste or the compost.

So, is there any future for the Native Guava? Rod says yes, and gas undertaken a range of actions to secure this plants future. Cuttings have been taken from the wild Mt Coot-tha population and struck in the nursery at the Botanic Gardens. These new plants are treated with a fungicide to remove the rust, and are then distributed to volunteer revegetation groups, to plant out “saviour” populations. These populations are located outside of the myrtle rusts preferred climatic zone, which “runs out of steam somewhere around Toowoomba, and further west where it gets drier”.

Rod says this is where gardeners come in. “We want to encourage people to grow this plant outside the range of the fungus”. By doing so, they will form insurance populations of this nearly extinct plant, and ensure it survives into the future. “It’s attractive but it’s not a widely cultivated plant”. It’s a shrub to a small rainforest tree, native to eastern Australia. The glossy leaves have a pineapple-like fragrance when crushed, and the berry is edible!


Myrtle rust is a serious threat to Australia’s rich biodiversity. The susceptible plant family (Myrtaceae) dominates many major Australian ecosystems and holds so many of our favourite native garden plants. By being alert to infections gardeners can help stop the spread. By planting out this native guava in drier areas, beyond the reach of the fungus, gardeners can help save this plant from extinction at the hands of an invasive, destructive interloper.

Controlling Disease on a Flax Lily

Flax lily (Dianella spp.) is a group of about 20 to 30 plants that feature attractive grass-like foliage and grows in U.S. Department of Agriculture plant hardiness zones 7 through 11. Flax lily has few problems but can come under attack by some common ornamental fungal pathogens such as rust, mold and mildew. Thankfully, these diseases are more annoying than anything else and rarely cause long-term damage.


The fungal pathogen Uredo dianellae attacks flax lily, resulting in what gardeners know as rust. Rust presents itself as reddish, purple, orange, brown or yellow masses of spores or pustules developing on leaves. Infected leaves can yellow or brown and begin to wither, curl and fall off the plant prematurely. Sooty mold is a black substance with a soot-like appearance on the foliage of infected plants. This annoying fungus requires honeydew — which is secreted by sap-sucking pests — in order to grow, and typically doesn’t threaten the life of the flax lily. Powdery mildew is most easily recognized by the white powdery growth that forms on the leaves of the infected plants. This extremely contagious fungal disease doesn’t require moisture to grow and water can actually inhibit the growth and spread of the fungal spores.

Organic Control

Fungicides won’t get rid of sooty mold and control requires managing the insects secreting the sticky honeydew. Insecticides are generally not recommended since they can cause more harm than good. Instead, attract beneficial predatory insects to prey on the honeydew-producing insects infesting the flax lily. Ladybugs and lacewings — which feed on aphids, scales, whiteflies, mealybugs and thrips — can be attracted to your garden by planting California poppy (Eschscholzia californica), cilantro (Coriandrum sativum) and parsley (Petroselinum crispum). Once you have controlled the insects, wash the sooty mold off the flax lily by spraying the plant with a water hose. If you don’t wash the sooty mold off the plant, it will slowly disappear on its own.

Chemical Control

Neem oil, horticultural oil and potassium bicarbonate are three fungicides that help control fungal diseases such as rust and powdery mildew. Each type of fungicide lists specific instructions, warnings and application rates that you should follow to improve its effectiveness and prevent damage to the flax lily. Unless otherwise stated on the fungicide label, the chemical should be applied on a day when the wind is calm, the temperatures are above 40 degrees Fahrenheit but below 90 degrees and when rain will not occur 24 hours after the application. If possible, spray the flax lily with the chosen fungicide at the first signs of infection.

Cultural Control

Most fungal diseases can be kept at bay by implementing proper cultural control methods in your garden. Proper spacing between the flax lilies and surrounding plants help to ensure good airflow. Air circulation dries leaves more quickly and reduces fungal growth. Also avoid overhead watering since it favors the germination and spread of fungal diseases such as rust. Instead, water at the base of the flax lily early in the day to allow the plant to dry before the sun goes down. Good sanitation also helps control flax lily problems; remove all plant debris that has fallen to the ground and prune infected plant matter off the flax lily.

Learn About Plant Rust Disease And Rust Treatment

Plant rust is a general term that refers to a rather large family of fungi that attack plants. Frequently, when a plant is affected by rust fungi, many gardeners feel at a loss as to what to do. Rust treatment as a plant disease is startling but can be treated.

Symptoms of Plant Rust

Rust fungi are very easy to identify on the plant. The disease can be characterized by a rust color on plant leaves and stems. The rust will start out as flecks and will eventually grow into bumps. The plant rust will most likely appear on the underside of the leaves of the plant.

The good news is that there are so many kinds of rust fungi and they are so plant specific, that if you see the rust color on plant leaves of one type of plant, you will not see it appear any other types of plants in your yard.

Rust Treatment for This Plant Disease

For rust fungi, prevention is the best defense. Rust thrives in a wet environment, so do not overwater your plants. Also, make sure your plants have good air circulation inside the branches and around the plant itself. This will help it dry its leaves faster.

If plant rust does affect your plant, remove affected leaves at the first sign of rust color on plant leaves. The faster the affected leaves can be removed, the better chance your plant has for survival. Be sure to dispose of these leaves. Do not compost them.

Then treat your plant with a fungicide, such as neem oil. Continue to remove leaves and treat the plant until all signs of the plant rust are gone.

Rust Control: How To Get Rid of Rust

Rust is a fungal disease that occurs on turf grasses when their growth has been slowed. Don’t let the name fool you, lawn rust is not the same as rust that appears on metals but merely is a name that was given because of the color of the lawn fungus resembling that of metallic rust. This lawn disease usually makes its presence felt in the late summer or early fall, during periods of dry weather or when the grass is low on nitrogen. Rust can also occur when there is an excessive amount of moisture or dew present.

Fortunately, lawn rust is largely a cosmetic issue that doesn’t harm your grass. The orangish powder spores which characterize this fungus appear directly on grass blades and can easily come off on shoes, clothing, lawn mowers or anything that touches it. This mode of transportation allows for the fungi to spread to other areas if not treated.

While it is an eyesore, you shouldn’t leave rust alone and just hope it goes away. Lawn rust can weaken the strength of the grass and make it vulnerable to other diseases and turf problems. If you have noticed rust on your lawn, our DIY treatment guide will show you how to eliminate it with professional fungicides.


Rust fungus is quite easy to identify on turf and can be diagnosed by simply pulling a couple of blades out of the turf. The blades will have orange reddish to yellowish brown dust or spores caked onto it. The lawn rust starts initially with the leaf blades turning yellow and gaining small yellowish spots which eventually turn orange, red or brownish in color. The spores can be rubbed off the grass blades with a finger.

Often, you will notice this rust on your shoes if you step on grass that has rust on it or on the blades of your mowing equipment after cutting the grass. All in all, patches of grass which are infected by rust disease will start to thin and become weaker compared to healthy unaffected grass

Rust lawn disease is caused by pustules and you can see the pustules when you look closely on the grass blades themselves and what happens is when you disturb them with your lawn equipment or step over them with your shoes, those pustules burst spores which get all over everything and then they’ll spread to the rest of the lawn as well as travel from lawn to lawn via commercial equipment.

Refer to the image above and our description to help you in identifying rust. If you are having trouble, you can contact us and we’ll help you in correctly ID’ing your issue.


Where to Inspect

There are a variety of plants which are vulnerable to suffering from rust fungus, from grasses to ornamentals to even evergreen plants. You can hardly miss rust problems on grass due to the ample amount of space the turf covers.

The spores of rust usually form when there are cool nights with heavy dew and frequent rainfall. Warm, cloudy, wet conditions followed by a hot day with high heat from the sun beating down also help to formulate spores. Basically, anytime the grass is not allowed to dry out after a period of 6 to 8 hours, rust on grass begins to form. Grass rust problems also appear more frequently when thatch in lawns is too thick or mowing is not carried out frequently enough.

What To Look For

It looks like an orangish brown powder that is caked onto grass blades and leaves. If you walk over your lawn, you usually will have the rust fungi come off onto your shoes.


Prior to treatment, we suggest wearing the proper safety equipment for the job to prevent chemicals from coming in contact with your eyes or skin. Gloves, safety goggles and long sleeved clothing should do. The best way to treat the rust on your lawn is applying fungicide a top the areas where you see it developed. What that is going to do is stop the disease in its tracks and help to clear it up faster.

Products which contain propiconazole (such as Patch Pro) and azoxystrobin (Systemic Fungicide RTS) are proven materials when have demonstrated to be very effective against lawn rust disease.

Step 1 – Measure and Apply

In a handpump sprayer mix the fungicide with water according to the label directions. Once mixed, spray the affected areas immediately. Use a fan nozzle setting so it creates a nice mist which will coat the rust evenly. What’s most important when applying any fungicide you select is timing and attacking the disease in its early stages. You may need to reapply the application after a period of 7-14 days to ensure the rust is totally gone.


Once the rust is gone, you will have to work to keep it gone by giving your lawn some much needed TLC. Mow your lawn at the proper height, aerate your lawn occasionally to reduce soil compaction and watering infrequently can help to keep rust and other lawn diseases off of your turf. You can also use Patch Pro as a preventative application late in the summer before it usually appears.

Key Takeaways

  • Rust is a lawn disease characterized by a brownish red powdery substance that is caked onto grass blades and other plants.
  • Our top recommended fungicide to control rust is Patch Pro. Timing is important when applying this product for best results.
  • Once your lawn has been treated, keep rust from returning with a consistent lawn care and maintenance program and applying a nitrogen rich fertilizer to keep your turf strong and healthy.

Mary asks: Some of the leaves on my plumeria tree have yellow spots on them and kind of orange bumps on the undersides. Eventually, these leaves turn totally yellow and drop off the tree. What is the problem and how might I get rid of it?


Mary asks: Some of the leaves on my plumeria tree have yellow spots on them and kind of orange bumps on the undersides. Eventually, these leaves turn totally yellow and drop off the tree. What is the problem and how might I get rid of it?

Tropical Gardener answer: It sounds like your plumeria is infected with the fungal pathogen, Coleosporium plumeriae, which causes the disease plumeria rust. The pathogen is host specific. Though it can and will spread to other plumeria, it will not infect other plant species. It was first identified on Oahu in 1991 and has since spread to all of the Hawaiian islands.

To get rid of the rust, start by inspecting your plant thoroughly and removing all the infected leaves, but not more than a third of them per week. Dispose of the leaves off your property. Do not compost them. Rust spores are easily spread. Spray the remaining leaves with a wettable sulfur mix to prevent rust attacking them. Wettable sulfur powder is available at most gardening stores and you should follow the directions on the package for mixing with water. If lots of the remaining leaves are infected, you might want to spray them with the broad spectrum bio-fungicide Serenade (also widely available). It contains a patented strain of Bacillus subtilis that controls fungal diseases and is approved for organic gardening.

Here are several recipes for low-toxic products that you can make yourself. One involves mixing water, baking soda, soap and neem oil. Mix 1 tablespoon of baking soda in a quart of water. Add 2 teaspoons of neem oil and about 1/4 teaspoon of Dr. Bronners peppermint soap to the water. Shake it to combine and spray all infected parts of the plant, especially the underside of the leaves. Of course, you can increase the recipe for larger plants. Spray every 7-10 days until you no longer see rust on the leaves.

Similar to other plant disease or pest issues, prevention is the best cure. This pathogen prefers warm moist environments. During our rainy season, conditions are ideal for rust to appear and spread, but you can take some preventive measures. Clean up all fallen leaves. The spores on infected leaves can be spread on the wind or by water.

Water in the early morning allowing time for moisture to dry out during the day. Be sure that all irrigation or watering goes into the soil not on the leaves. Damp leaves are especially vulnerable to disease.

Soft, leafy, new growth is also a prime target, especially when it results from a heavy dose of nitrogen fertilizer. Use a slow release product with a balanced N-P-K to provide good nutrition and control new growth. A thick layer of mulch or organic compost on the soil surrounding your plumeria can improve soil and plant health and serve to prevent rust spores from splashing onto the leaves.

Keep weeds down around your plumeria and allow space between plants to keep humidity levels low. Though you probably don’t currently have a resistant plumeria variety, several do exist. Lots of information on the disease and a list of resistant varieties can found on a UH free publication titled “Plumeria Rust” which you can find at https://www.ctahr.hawaii.edu/oc/freepubs/pdf/pd-61.pdf.

Email plant questions to [email protected] for answers by Certified Master Gardeners. Some questions will be chosen for inclusion in this column.

Diana Duff is a plant adviser, educator and consultant living in a dryland forest north of Kailua-Kona.

Gardening Events

Tuesday: “Adding Commercial Yeast to Coffee Fermentation,” 4-5:30 p.m. at UH Cooperative Extension Service office in Kainaliu across from the Aloha Theatre with Kevin McHale of Scott Labs. Demonstration of process using commercial yeast. The preferred yeast product will be available at the event. Sponsored by Kona Coffee Farmer’s Association. Info: Visit “events” at www.konacoffeefarmers.org.

Saturday: “Work Day at Amy Greenwell Garden,” 9 a.m.-12:30 p.m. Meet at the Garden Visitor Center across from the Manago Hotel in Captain Cook. Volunteers will be able to help with garden maintenance and are invited to bring a brown bag lunch. Water and snacks provided. Info: Call Peter at 323-3318.

“Basic Grant Writing Workshop,” 9 a.m.-4 p.m. at UH-Hilo UCB331 with Jeani Navarro, who has more than 30 years of grant-writing experience. $85 registration fee. A 50 percent discount is available through the Employment &Training Fund. Info: Call 932-7830 or visit https://hilo.hawaii.edu/ccecs/

Farmer Direct Markets

Wednesday: “Sunset Farmers Market,” 2-6 p.m. in the HPM parking lot, 74-5511 Luhia St., in Kailua-Kona

Wednesday and Friday: “Hooulu Farmers Market,” 9 a.m.-2 p.m. at Sheraton Kona Resort &Spa at Keauhou Bay

Friday: “Pure Kona Market,” 9 a.m.-5 p.m. at Amy Greenwell Garden in Captain Cook

Saturday: “Keauhou Farmers Market,” 8 a.m.-noon at Keauhou Shopping Center

“Kamuela Farmer’s Market,” 7 a.m.-noon at Pukalani Stables

Sunday: “Pure Kona Green Market,” 9 a.m.-2 p.m. at Amy Greenwell Garden in Captain Cook

Tuesday-Saturday: “U-Pick greens and produce,” 10 a.m.-4 p.m. at Tropical Edibles Nursery in Captain Cook

Plant Advice Lines

Anytime: [email protected]


Tuesdays, Thursdays: 9 a.m.-noon at UH-CES in Kainaliu at 322-4892

Mondays, Tuesdays, Fridays: 9 a.m.-noon at UH-CES in Hilo at 981-5199 or [email protected]

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