The South’s Daylilies: Daylily Rust Observation and Treatment Options
Here at the Lily Farm, 2012 was a crucial year for rust in the south. Numerous advancements have been made in the treatment of rust, and a long-term solution may be bubbling to the surface. Based on our observations at the Lily Farm, this post will try to provide you some choices for handling rust.
Let’s describe daylily rust, also known as “puccinia,” to help folks who are unfamiliar with daylilies. According to the AHS Daylily Dictionary, rust is as follows: The fungus Puccinia hemerocallidis causes daylily rust, which affects the leaves and scapes. Daylily rust has an orange tint that resembles pimples and spreads quickly, making it very conspicuous on the leaf of the plant. It spreads primarily through the wind, although it can also spread through direct contact and other means. Most crucially, due to the ease with which it spreads, once you have rust on one plant, you very certainly will also have rust on all of your daylilies.
The good news for people who live in Zone 6 or lower is that rust has not demonstrated the ability to overwinter, which means that any rust that may exist in plants does not manifest itself visibly as a result of the extended cold that Zone 6 or lower experiences. In other words, even if you have plants that have rust, once they have spent the winter, the plants won’t exhibit rust the following year. Rust will reappear in the spring or summer depending on how harsh (or not) the winter was, although in Zones 7 and higher, winters are not severe enough to prevent rust from effectively overwintering. For instance, the winter of 2010 was extremely cold here at the Lily Farm, with numerous days with lows of 20 or lower. Up until mid-June of the next spring/summer, we never noticed any rust. Rust was first noticed at the farm in mid-February of this year—the earliest it had ever been seen—and spread quickly because of the ideal mild and wet circumstances in our region, in contrast to last winter (2011) when we had nearly no days below 32.
What are my alternatives if I have rust, then? is the query I hear the most. The remainder of this post will focus on that. There are some intriguing products on the market, including one that might actually totally eradicate rust in plant tissue. Progress is being made in this area. The following are some remedies for rust:
- The most often used technique? common gardeners? To avoid spraying, let the rust die off over the winter. Then, in the spring, when the scapes are at least halfway up, cut the foliage back to a height of 6 inches. Even though I knew it would look bad, I nevertheless did it in the front yard of my house in the garden. To my surprise, this actually made the blooms the center of attention, which encouraged more people to stop and inquire about “what is that pretty flower?” than I’ve ever had before! Actually, I was rather happy with this approach.
- Do nothing at all. Although daylilies are not killed by rust, it can be exceedingly unattractive. This is not the option for you if you want to enjoy lovely foliage all year round. However, if you have a decently cold winter, you may be able to avoid dealing with rust until bloom season is over. At that point, many people decide to let the rust continue until the summer heat stops it (generally 97 degrees seems to be the point at which rust stops forming on the foliage based on my own local observations). The scapes are impacted by rust, but the blooms are unaffected.
- Spray only when necessary. Many people decide to take it easy after the winter and wait until they notice the first indications of rust. They will then immediately spray with a fungus to stop the rust in its tracks at this stage. In a later section of this article, the spraying options will be discussed. The rust that is already visible on the plant must be killed with a contact spray, and the rust must be suppressed within the plant with a systemic spray in order to prevent it from showing up on the leaf. Spraying merely a systemic won’t work if you have rust. A contact spray is also necessary. You may decide to ignore rust after bloom season is done because most of us in the deep south will experience those 97°F or greater temperatures by June. If so, rust won’t likely appear again until the fall, usually in October or November, when the temperature falls below 97. The winter will take care of it for you if you choose to do nothing or reapply the spray as previously mentioned.
- Spritz continuously. If you never want to see rust on your plants, this is the strategy to use. Of course, this is the most expensive choice because systemic sprays with a history of success are also highly expensive. But even so, this approach is THE ONLY way to guarantee that your daylilies won’t rust. Many people may constantly spray on cycles of 15 to 20 days until they get a strong freeze (28 or below). When winter is done, they will stop spraying, and once the weather starts to warm up, they will resume their work EVEN PRIOR TO THE APPEARANCE OF RUSS. This is THE METHOD that will allow one to entirely rid their plants of rust, along with certain commercial solutions that I will detail later.
Here are some guidelines for daylily rust spraying that everyone should be aware of. It is crucial to remember that practically all spraying guidelines call for alternating fungicides according to their mechanism of action. Therefore, while spraying for rust, mix in additional products with a different mode of action, such as Banner Max, Strike, Bayelton, etc., in addition to Heritage.
First, whenever rust is noticeable on the daylily leaf, a CONTACT spray MUST BE USED FIRST. Daconil and Mancozeb (also known as Dithane) are contact fungicides. Even though it is not a fungicide, I have discovered that standard Dawn Dishwashing Soap works well as a contact spray for active rust.
After that, a SYSTEMIC spray MUST be utilized ALONE or WITH a contact spray (ie, you can mix the contact and systemic together and spray at the same time). Here is where it seems like there has been a MAJOR advancement in the treatment of rust. The systemic fungicide Cabrio, which comes in both liquid (Headline) and powder form, appears to actually destroy the rust in the plant tissue. Headline actually states that when applied at maximum strength for 5 consecutive sprayings, it will entirely eradicate daylily rust, although this has not yet been supported by documentation. We have followed this spraying schedule at the farm this year, and we won’t know for sure whether the plants are rust-free until the following spring. I also add Dawn to any systemic spray I use to serve as the contact spray (usually 1 teaspoon Dawn to 1 gallon of water).
Many people have also expressed concern about the rust-removal sprays that the “ordinary” gardener may purchase without spending a lot of money on high-end brands. This year’s surprise in my Nacogdoches home garden was yet another one for me. At Lowes, I paid around $5 for a spray called Garden Safe Spray III that is available over the counter. In my backyard garden, I initially used Dawn spray to treat plants that already had rust before using Garden Safe Spray. The end outcome was that the rust was still present on the plants, but it was largely at levels that were visually acceptable. With regard to how the foliage appeared to me from a distance, it did not stop the rust, but it did prove to be acceptable. In the home garden as of now now (August), the identical plants don’t show any signs of rust, but I do anticipate that this fall they will. Having said that, it seems that some “over the counter” fungicides with rust-specific labels—typically rose rust on the label—do a respectable job of inhibiting rust. Of course, another alternative is for certain clubs to purchase a product like Cabrio and divide the cost among the members, cutting the cost per use for each member.
Other conclusions I’ve drawn from experiments conducted at the farm include: a) Rust needs water to form on the foliage. Rust will spread more slowly the more water the plants are deprived of above ground. By keeping the foliage wet, overhead watering creates the ideal environment for rust to form. It would be best if you could water the plants using drip irrigation; alternatively, you might get plants that seem to be rust-free but aren’t necessarily. The rust might be dormant in the leaf when you receive a fresh plant. Many gardeners decide to confine these plants in pots and keep them apart from their other daylilies until they have experienced a full winter. I support this approach out of caution, and c) many plants originate from nurseries that are “rust free.” Again, though, this does not imply that the plants will be free of rust. For instance, a nursery that uses continual spraying will never notice rust on its farm and can ship their plants with the assurance that they are “rust free.” I believe that if a nursery sprays for rust for any reason, they most likely once had rust. The use of Cabrio/Headline, which may genuinely eradicate rust in the daylily, may modify the old rule that if a plant had rust, it will ultimately exhibit it again. d) try not to plant your daylilies too close together, as this also helps reduce the spread of rust; e) I am suspicious of claims that there are plants that are “rust proof.” Once again, this has not been proved, although tests here at the farm are proving to be quite hopeful in this area. Only a small portion of the daylilies on our farm, which totals more than 5 acres, demonstrated exceptional rust resistance. However, even those who were continuously exposed to it over time began to display at least minor signs of rust. Therefore, just to be safe, I would treat every new plant as though it might have rust. While some plants are more resistant to rust than others, based on my findings at the Lily Farm, the bulk of daylilies available today are, at best, average in this regard.
In conclusion, exciting progress seems to be being made as we assess fungicides and their impact on rust in our favorite daylily. Since most people buy their plants for the beauty of the flower rather than the rust, I am finding that the general public is not nearly as upset by it as collectors were initially. Instead, they choose to ignore it. This also applies to people who want their plants to be chemical-free. But as rust control in the South is ultimately crucial to being able to develop this market to the typical customer, devices like Cabrio and Headline provide vital advances for the future. They should ideally be able to purchase plants where rust is not a problem. The truth is that for the majority of us, nothing on earth compares to the variety of flowers that our beloved daylilies provide us, thus we will never part with them! LIFE FOR HEMEROCALLIS!
What remedy is there for daylily rust?
A central, yellow streak that frequently begins at the leaf tips and moves downhill along the leaf midvein are the first signs of daylily streak. Necrosis in the surrounding green tissue and the yellow streak itself appear after the original streak. On diseased leaves, little reddish brown specks and oval, elongated necrotic lesions appear. Foliage that is ill may entirely wither and pass away. By buying disease-free stock plants and only reproducing from healthy plants, daylily streak can be avoided. The susceptibility of different cultivars to this disease varies, making careful variety selection crucial for disease control. Since splashing water is the main method of transmission for daylily streak, maintaining correct plant spacing and reducing overhead irrigation can retard the disease’s progress. Additionally, the disease can be spread by personnel and equipment, particularly when the leaves are damp. When it is warmer than 90 degrees Fahrenheit, leaf streak does not form. Separate the diseased plant matter from the healthy daylilies. Effective fungicides include thiophanate methyl (Cleary’s 3336, FungoFlo), myclobutanil (Eagle), chlorothalonil (Daconil, Echo 90DF), and azoxystrobin. Fungicides can be used to protect vulnerable young foliage (Heritage).
What fungicide works the best against rust?
Mild temperatures that encourage the growth of the host are favorable for rust infections. High temperatures have the ability to kill rust spores. Hot water treatment of cuttings can successfully treat some rust diseases, such as geranium rust (Puccinia pelargonii-zonalis), although some host damage may result.
When rust is an issue, overhead irrigation should be avoided since water is required for infection. Take away alternative hosts.
A program to eradicate the rusts Puccinia horiana, which causes Chrysanthemum white rust, and Uromyces transversalis, which causes Gladiolus rust, is in place in California. Other members of the iris family, such as Crocosmia, Tritonia, and Watsonia, are also affected by the disease caused by gladiolus rust. The DISEASE CONTROL OUTLINE FOR CHRYSANTHEMUM and DISEASE CONTROL OUTLINE FOR GLADIOLUS contain detailed instructions.
A variety of fungicides are available for use in preventing infections in plants. Triadimefon is only effective against particular rusts, but mancozeb as a protectant and myclobutanil as an eradicant are typically effective against all rusts.
Not all pesticides with registration are listed. The following are presented in order of the pesticides’ IPM values, with the most potent and least likely to result in resistance at the top of the list. Consider the qualities of the pesticide, when to apply it, how it will affect honey bees, and the environment when selecting a pesticide. Always read the product’s label before using it.
COMMENTS: An eradicant and preventative systemic fungicide used as a foliar spray.
COMMENTS: Only offers defense; must be applied before to infection. defends against rusts, blight, leaf spots, and botrytis. Control requires complete covering.
COMMENTS: A systemic fungicide used as a foliar spray; it protects against and eradicates powdery mildew or rusts on carnations, crape myrtles, gerberas, roses, and snapdragons.
Carboximide (7) and quinone outside inhibitor are members of the MODE OF ACTION GROUP NAME (NUMBER1) (11)
In greenhouses and commercial nurseries, a long-lasting systemic fungicide that provides general control of some powdery mildews, some rusts, and leaf blight and spots. This substance can be hazardous to some plants, such greenhouse roses, because it is closely related to substances that impede growth.
COMMENTS: Spray the plant’s foliage or crown with a banded or dispersed application. a systemic fungicide that works against rusts locally.
SUGGESTIONS: Apply a wetting agent. Not as powerful as other options. When temperatures are higher than 85F, use this material with caution.
COMMENTS: Prevents chrysanthemum white rot, however some cultivars may experience phytotoxic effects.
COMMENTS: Neem has some rust-protective characteristics and is registered for ornamentals for gardens and nurseries, however it is ineffective for rust on roses. 14 days are given for applications.
The Fungicide Resistance Action Committee (FRAC) assigns group numbers based on various action types. In a program to manage resistance, fungicides with a different group number might be used in alternating cycles. In California, fungicides with mode of action group numbers 1, 4, 9, 11, or 17 should only be applied once before switching to a fungicide with a different group number; fungicides with other group numbers should only be applied twice in a row before switching to a fungicide with a different mode of action group number.
Unless otherwise stated, the restricted entry interval (REI) is the number of hours after treatment before it is safe to enter the treated area without wearing protective clothes.