October is the Best Time to Deal With Black Spot on Roses – Here's How to Reduce Problems Next Year

While the garden is gradually quietening, October sees a second flush of rose blooms from repeat flowerers such as Hybrid Teas and Floribundas. Softly glowing, their flowers appear more abundant and last longer thanks to the cooler temperatures and moist conditions.

From afar, each plant may appear to be healthy and thriving but it's well worth taking a closer look. If you spot a peppering of black spotted yellow leaves, now is the time to take urgent action.

A crucial element of rose care and growing these romantic plants, is identifying and dealing efficiently with pests and diseases. Black spot is perhaps the most prevalent threat to rose health but thankfully October is the best time to deal with it. A thorough clear up now, and for that this Telescopic Leaf Grabber from Walmart is handy, will encourage good plant health and help prevent the disease reoccurring the following season.

Why Clear Up Diseased Rose Leaves

There's no ignoring blackspot once it appears on your roses. Purplish blotches first appear on the leaves and spreads with a raggedy edge while the rest of the leaf gradually yellows and falls.

'Black spot is caused by the fungus Diplocarpon rosae, which can overwinter on infected leaves and plant debris beneath roses. If that material remains in the bed, rain or irrigation can splash spores from the infected debris onto the rose’s lower leaves,' advises Wes Harvell, Rosarian, Jackson & Perkins.

Hard to kill and with constantly evolving strains, this rose disease spreads through rose foliage and stems, severely weakening the plant and drastically reducing blooms. Even new cultivars that are bred to be blackspot resistant have eventually succumbed to the harmful spores, as the disease adapts over time.

Knock Out Roses, including Peachy Knock Out from Perfect Plants , are well regarded for their disease resistance, having been genetically tweaked to make it harder for problematic fungal spores to take hold.

Blackspot spores are quick and easy to spread through wind and water, so eliminating the source is a wise measure, as Wes advises.

'Removing and destroying infected leaves at the end of the season can reduce one of the sources that could cause a new infection to begin. October is a particularly useful time to pay attention to clean-up because roses in colder climates are beginning to enter dormancy and shed foliage naturally.'

Quick And Easy Leaf Clear Up Tricks

Removing blackspot infected rose leaves and stems is a task on the fall gardening checklist that is well worth spending time on.

'Start by removing infected leaves still attached to the rose, then thoroughly rake and collect fallen foliage and debris from around the base of the plant,' advises Wes. 'Avoid doing this work while plants are wet, as moisture help black spot spread.'

Gently removing blighted leaves by hand is the simplest and most effective method, but wearing thick gloves, such as these Pro Rose Gloves from Lowes, is a must, as Wes suggests. 'Wear protective gloves when working around roses, both because of thorns and because you’re handling diseased material. Also, be sure to wash your hands thoroughly after handing a black-spot-infected rose so you don’t accidentally spread fungal material elsewhere in the garden.'

Gathering fallen rose leaves can be a laborious job to do by hand, and there are plenty of leaf-clearing tools to use, but it's crucial to disinfect and clean garden tools afterwards, to prevent transferring spores around the garden. Retainer Cleaner and Lubricator from Walmart is handy option for pruners, loppers and garden snips.

Always avoid using a leaf blower near infected rose leaves as this is an easy way to spread the spores.

How To Safely Dispose Of Infected Foliage

What to do with infected rose foliage is a popular question many gardeners ask. Given the ease with which the spores spread it is imperative that they are disposed of efficiently and responsibly.

'Do not compost them and don’t leave them lying in the garden,' insists Wes. 'Put black-spot-infected leaves directly in the trash because spores can survive on fallen foliage. If diseased material remains beneath the rose, it can become a source of reinfection.'

He also suggests that it's well worth refreshing your mulch afterwards too. 'Adding a layer of mulch can help prevent rain or irrigation from splashing fungal material from the soil back onto the foliage.' One of the best mulch for roses is cedar bark chips - find this naturally insect repelling mulch at Walmart.

Bag up infected leaves and place them in your household garbage. If you have large quantities of foliage check your municipality's official website for curb-side pickup programs and drop off sites for municipal recycling.

While most garden cuttings can be successfully home composted, this is not advised for blackspot as most heaps do not produce the high or constant heat of 140°F (60°C) needed to destroy the fungal spores.

Instead, you can bury them in the soil, leaving them to rot down naturally. Just be sure to chose a spot where they will remain undisturbed and dig down to a depth of 1 ft (60cm).

Controlled burning of blackspot infected leaves can be carried out in some areas, but always check the local fire codes, active burn bans and neighbourhood permissions before proceeding. A lidded yard incinerator, such as this Yard Tuff Burn Cage from Lowe's is a neat and safe choice.

What To Shop

Tackling this rose care task in October will not only encourage healthier plants and more plentiful blooms next year, but save you time and effort discouraging persistent rose pests too.

A classic plant choice for cottage garden ideas, why not seek more design inspiration from landscaping with roses.

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Meet the Expert

Wes Harvell

Wes is horticulturally educated with over 30 years in the rose business as a salesman, merchandiser, marketer, and online retailer. He is currently the rosarian for the collection of JPPA Inc., garden brands: Jackson & Perkins, Wayside Gardens, and Park Seed.