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Crown Rot

Many theories exist as to the causes of crown rot. Excessive heat and humidity seem to be the triggers. Gardeners who have experienced crown rot will understand the frustration of seeing once healthy plants dying while daylilies all around are thriving.

If a healthy plant suddenly turns yellow, pull out a leaf and you can tell by the foul smell that it is crown rot or indicates crown rot.
Fortunately crown rot is not wide spread. In addition, some cultivars are more prone to the disease than others.

If seen early enough the use of a fungicide can help. Some people use Dettol or bleach, mix about twice the recommended strength and drench the plant every day for a week. You may also have some success with digging the plant, removing the infected part, and dusting the remaining plant with sulphur or a fungicide. Then plant in another area. Treat the infected site by removing soil and disposing of it. Treat the area with a fungicide drench.

Keeping the immune system of a plant healthy will help protect against many diseases.

Daylily Rust (Puccina hemerocallidis)

Daylily rust is native to Asia, and was detected in the USA in 2000. It can survive in a wide range of climates and could establish in Australia anywhere that daylilies are grown. Rust spreads very easily on the wind currents and on almost any surface, including clothing and machinery. This means that the disease is generally not conducive to eradication attempts.

Symptoms and hosts: The symptoms vary depending on the variety of daylily affected and the stage of rust present. Generally, the pathogen causes raised yellow rust brown spots or streaks on the underside of leaves, which may contain a mass of fine powdery spores, the fruiting bodies of the disease. It could be confused with the common daylily streak disease (aureobasidium microstictum), which causes more elongated yellow brown streaks on the leaves, often towards the midrib. Daylily streak does not produce the characteristic masses of yellow brown spores associated with rusts.

Daylily rust is heteroecious, requiring two different hosts to complete its life cycle, which includes up to five different spore stages. Patrina and Hosta SPP have been reported as alternate hosts. However, no rust infections have been found on these plants in the USA.

Daylily rust survival and spread is not affected by the absence of alternate hosts and it can continue to infect daylilies from year to year with completing its life cycle.

Control: Daylily rust has spread rapidly in the USA, despite tough regulatory action against it. Therefore, it is possible that you may see this disease in your garden or nursery in the near future. The following includes some practical measures you can take to control and slow the spread of daylily rust.

Carefully remove and destroy (preferably bury) infected foliage from plants on which the rust is detected and all remaining plants in the block or bed. Apply a fungicide program using chemicals registered for control of rust in ornamentals. Rotate between applications of different chemicals, particularly if using sytemics to avoid the disease becoming fungicide resistant. There is a considerable range of susceptibility among varieties with some appearing to be largely unaffected by the diseases. Consider complete, but careful destruction of varieties that have been severely affected, in order to protect less susceptible plants from high inoculum pressure and possible disease development.

Daylily rust can spread far and wide by wind, on infected plants, or on almost any surfact that comes into contact with spores. The only practical way to slow or prevent the spread of the disease is to implement control and hygiene measures to reduce inoculum production and movement and by ensuring that plants you are selling or moving do not have rust symptoms

SCAPE BLASTING IN DAYLILIES

Many people have theorized that excessive water brings on scape blasting. It occurs before bloom season, but does not always result in the scape being completely broken off. If the latter is the case, the best thing to do is break it off completely

Excess Water Suspected.

Excess water seems to aggravate a problem, which appears to be associated with excessive growth and swelling of the brittle scape. If you water every day, or almost every day, most likely this will be excessive during the period your scapes are developing.

It seems likely that excess fertilizing may also contribute to scape blasting.

I have read where scape blasting seems to be less serious on established clumps of daylilies than on single fans. It is harder to overwater or over fertilise a clump than it is a single fan.

I have also heard that if the broken scape is removed as soon as it starts to break you will most likely get a subsequent scape and extend your season.

There appears to be some evidence from material already published that scape blasting appears more amongst Tetraploids than Diploids. I have not heard or read of any scientific study being made to look into this matter. Some say that it could be a gene problem.