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Control methods on common diseases of roses

Control methods on common diseases of roses

2020-01-09

Roses are easily damaged by various diseases. Following are some common diseases of roses.

Powdery mildew:

Powdery mildew is a severe problem in new leaves of roses, which shows salient leaves with pale white powder. Leaves are uneven and curl. What’s worse, bacteria spread and entire blade back is covered with gray mold.

It is recommended to apply with fungicide ‘Qingcui’ (difenoconazole 15% + pyraclostrobin 25% SC)


Gray mold:

When gray mold occurs in leaves margin and leaves tip, water-stained hazel spots appear at first, sag slightly, then spots spread and turn rot.

When gray mold happens in flower buds, gray-black spots appear to flowers from opening. Finally, damaged buds turn brown and wilt.

When the flowers are infringed by gray mold, water-stained small spots begin on petals or petals tips and edges become brown, which rapidly wilts and rots. Eventually, whole flower becomes brown and withered.

It is suggested to used fungicide ‘Kaymery’ (pyraclostrobin 13% + boscalid 25% WDG) to prevent and control gray mold.


Downy mildew:
Downy mildew usually harms leaves, new shoots, stems, pedicels and petals of roses.

In the beginning, irregular pale green streaks appear on the leaves surface, and lesions expand, showing yellow-brown and purple. And then leaves spots turn to gray-brown, with darker edges, gradually withered or shed, Finally, diseased shoots became dry.


It is also recommended to apply with fungicide ‘Qingcui’ (difenoconazole 15% + pyraclostrobin 25% SC) or fungicide ‘Qitai’ (pyraclostrobin 5% + metiram 55% WDG)


Rose spot diseases

Rose leaves, new shoots and pedicels can be affected by spot diseases. Damaged leaves fall off easily. When the spot disease occurs severely, all the leaves in lower and middle parts fall off, leaving only a few new leaves on the top.



Fungicide ‘Wonderland’ (Tebuconazole 133g/L + Prochloraz 267g/L EW) is a suitable to applied to roses to control spot diseases.

Rust:
Rust often brings harm to buds, leaves, twigs, receptacles, pedicels and flowers of roses. Rust is most obvious on leaves, which shows rusty powder particles. But some lesions are still grayish green, with black spots on upper parts. More severely, leaves fall off.


It is a good choice to use Fungicide ‘Qitai’ (pyraclostrobin 5% + metiram 55% WDG)


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