Understanding and Treating Cedar Apple Rust

Garden Caregarden TriviaPlant Health CareUncategorized
Written By Peter Morris

WHAT IS THAT !

Fungal blisters on apple leaf

 As the summer progresses into fall gardeners start noticing these blisters on their apple tree leaves.  It's a fungus !!! This disease is one of several caused by the genus Gymnosporangium.Its called Cedar Apple Rust. 

Life cycle on broadleaf plants

 The disease  has a complex life cycle.  It spends part of its life on a juniper or cedar and part on one or more hosts in the rose family, requiring both to complete it’s life cycle. If prefers broad leaf plants like Malus (apple, crab apple), Amelanchier, pear, roses, and evergreens ones like cedars and junipers. 

Damaged Crabapple fruit

 In the broad leaf plants, spores infect leaves, fruit, and soft stem tissues in early spring.  They grow and produce bright yellow or orange lesions by late summer.  Heavily infected leaves and fruit fall off prematurely. 

Hawthorne leaf with blisters

The fungal genus also contains species that damage pear (above)

 During dry weather, these lesions on the broad leaf trees disperse spores which spread by wind and infect nearby junipers and cedars. 

Lesions dispersing new spores

Lifecycle on evergreen plants

 Galls form on the evergreens where it survives the winter.  It may take more than a year for the galls to reach maturity. Once ready, in the early spring, bright, orange, gelatinous, horn-like growths 1-2 cm long emerge from the galls. These structures produce spores, which spread by wind to infect the broad leaf host in the spring, repeating the two host cycle. 

Cedar Apple Rust gall on Arborvitae

Treatment

 CAR is extremely difficult to eradicate and can only be controlled by applying several treatments of fungicide during Spring and early Summer on both broad leaved and evergreen plants.  Because the spores are so prevalent in the environment, treatment has to be repeated every year.  Specific synthetic fungicides are available to treat CAR in the apple family but these must be applied as soon as the flowers fade and be repeated 4 times about 3 weeks apart. As this can become extremely expensive, we suggest moving towards  using CAR resistant varieties. 

If you see any on your trees - Call Plant Specialists TODAY !

We have experts that know what to do !

They are NYSDEC licensed applicators and can treat them too !!!

Don't delay – the sooner the better !

GREENING NEW YORK FOR OVER 51 YEARS !

   Article written by our Staff Horticulturist, Peter B Morris, BSc, MSc, MBAAll photographs used with permission @SHUTTERSTOCK   

Peter Morris

Peter was born and raised on a beautiful green island in the midst of a tropical rainforest. He was introduced into the world of plants at the age of six when his grandmother, an avid Spanish gardener herself, asked him to help her grow seeds for her pepper garden. He was hooked! By the time he was a teen, he had his own rose and orchid collection numbering in the hundreds. Botany was in his blood, and that is what he set out to study.

His passion brought him to NY in the late seventies to further his education. His tenacity allowed him to work full time at Plant Specialists while he completed a MS in Plant Biology. As a manager at the time he felt unsatisfied with his knowledge of business and business processes. Peter felt compelled to learn, so he then pursued and completed an MBA in Quality Management within a few short years.

Peter’s other passion is teaching. His natural ability is quickly consumed by our staff in all subjects in Botany, Horticulture, and Landscaping. He created an immense reference library of more than 3,500 plants providing an invaluable resource for our staff.

Peter’s breadth of knowledge and wisdom allows him to effectively diagnose the needs of plants. Sometimes just by walking into a garden he can create a prescription that fixes even the hardest issue. He is our Staff Botanist, Diagnostician, and all around Mentor. Recently, he has put his immense knowledge and skills into developing a new department that focuses on Plant Healthcare. As he puts it, “Magic through Science”. The PHC staff that surround him have avidly consumed his teachings. Substantially developing their own plant wisdom, many have taken on difficult plant health issues with spectacular results.

Plant Healthcare has been an instant success with customers! The proper treatment of insects and diseases including Organic methods has made pest control a necessity for every plant. Correcting hormonal imbalances caused by planting in containers or refurbishing soils leached of nutrients by irrigation systems are big challenges PHC has become quite comfortable addressing. The scientific approach to the complex demands of keeping plants healthy in our harsh city environment has made many a customer say WOW!

Previous

ESSENTIAL OILS
Next

What Is Cauliflory and Why Does It Matter?