Knock Roses appear to have crown/root rot

Yard

11/1/2020 – After the wind from Hurricane Zeta blew the south side of the large Knock Out rose immediately west of the front porch the blackened stalks in the center and dead canes were more visible. Cut them out.

Research into why the azalea in the backyard row has dead stalks lead to understanding about crown or root rot. That looks like what is happening to this rose as well as one along the kitchen wall near the Frescati that mysteriously died.

Also found good info about root rot with roses here.

Poured hydrogen peroxide mixed in water all around the rose stump.

11/4/2020 – Sprayed the canes with Mancozeb to hopefully stop the spread. Noticed a few black canes on the other Knockouts so sprayed Mancozeb and watered all Knockouts on either side of the front porch with 3:1 hydrogen peroxide and water.

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