What are those spots on my Boston ivy ?

Design and InstallationGarden Caregarden TriviaIndoor plantsPlant Health CareUncategorized
Written By Peter Morris

Guignardia bidwellii - that's the cause !

brown spots occur singularly here - and the dried out tissue then breaks, and forms a hole

Our beloved Boston ivy that everyone wants planted to grow up bare fences, walls and parapets gets an ugly fungal spot in the summer. It shows itself as a round light-colored area or darkened spot that is bordered in bright red or reddish-brown tint. 

The culprit

Guignardia leaf spot is caused by the fungus Phyllosticta ampelicida (formerly Guignardia bidwellii), which survives in leaf litter. Spores of the fungus are produced under cool, moist conditions and can be dispersed by wind or splashing water.

This particular leaf spot is a common fungal leaf disease that affects vining plants such as Boston ivy and Virginia-creeper. The fungus also a leaf spot and fruit rot of grape called black rot – a dreaded grape growers disease ! 

Observations

It can occur in clusters or sporadic across the leaf. Mostly a shade problem it will occur in full if there is a stress from insufficient soil, water or nutrients. In severe cases it will cause defoliation in mid summer.Sometimes it will tint broad areas in bright red before forming spots. 

reddish leaves with spots is not a good sign in mid season

What to do !

DO NOT panic! This leaf spot is mostly a cosmetic disease, making an affected plant look a little ragged, but not killing the plant. Only occasionally will the disease be more severe, resulting in defoliation.

It is better to treat the issues of nutrition and light deficiency before attempting to control with fungicides. Keep in mind a drier environment is less favorable for disease developments. Water plants at the base using a soaker or drip hose to minimize wetting of leaves and reduce the movement of spores. 

severe case of reddish leaves with many spots

Treatment

If a plant has been severely defoliated preventative fungicide treatments may be necessary the following season.

Make an initial fungicide application as leaves first begin to emerge. If the weather is cool and wet, make additional applications at seven to 14 day intervals until hotter, drier weather develops or until leaves are fully expanded and mature.

We at Plant Specialists prefer to use an organic copper product. 

Got spots?

Call us - we know what to do !

PLANT SPECIALISTS

GREENING NEW YORK FOR OVER 53 YEARS !

Article written by our Staff Horticulturist, Peter B Morris, BSc, MSc, MBA

All 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!

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