Daylily Rust: The fungus Puccinia hemerocallidis is the culprit behind daylily rust. Yellow to brown streaks on the leaves and numerous little yellow spots are the symptoms, which are similar to those of daylily leaf streak.
The development of tiny orange pustules on the underside of leaves, however, is a sign unique to daylily rust. The yellowish-orange urediniospores that disseminate to infect additional daylily leaf are produced by these pustules. These spores may be spread by wind or by gardeners who handle sick plants. Rust on daylilies can spread quickly.
Examine and buy plants that are free of disease, paying special attention to the lower leaf surfaces. The spores will rub off when rust-infected foliage is cleaned with a white tissue and leave a yellowish-orange stain.
Look for and cultivate varieties that are resistant. Steer clear of overhead irrigation. Fall is the time to trim the dead leaves from daylily plant bases and dispose of it.
Plants may be sprayed with propiconazole, myclobutanil, or chlorothalonil to help reduce daylily rust. Spray as needed every two weeks, and also spray after pruning plants. During the blossoming season, avoid using chlorothalonil spray. Examples of brands and goods can be found in Table 1.
How can rust on daylilies be prevented?
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 throughout the winter. Then, in the spring, when the scapes are at least halfway up, cut the leaves 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 really made the blossoms the center of attention, which encouraged more people to stop and inquire about “what is that wonderful 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 time, 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 subsequent section of this text, the spraying alternatives 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!