Because many rose diseases are caused by fungi, take precautions to keep the leaves dry and air circulation adequate. Some basic guidelines include:
Telltale signs include dark brown, purple or reddish spots on the leaves, stems or canes. White growth may appear on the underside of leaves and leaves may turn yellow and drop. It often develops when relative humidity is above 85% and temperatures range from 45-80°F. Because it develops so rapidly—it can infect a rose in three hours of favorable conditions—prevention is key.
Immediately after planting, apply a soil drench with Subdue. Then spray weekly using a rotation of fungicides, taking care to spray the undersides of leaves.
The best defense is to provide good ventilation for the plants and to keep the leaves dry.
During the early spring, follow these recommendations:
If symptoms of downy mildew appear, remove the affected plants immediately.
Powdery mildew looks like white fuzzy powder and accumulates on leaves and stems. In addition to the white or gray growth on leaves, shoots and buds, other signs include leaf cupping, distorted leaves and purplish blotches on the underside of leaves. New leaves are most susceptible.
Powdery mildew usually develops when daytime temperatures warm to 50-80°F, nights remain cool, and relative humidity exceeds 90% at night.
Preventative measures include:
Rust appears as orange or rust-colored growth on the bottom of leaves. Older leaves usually show symptoms before younger leaves. The entire leaf may turn yellow and defoliation may occur. Rust usually develops in mild temperatures and moist conditions. It is spread by wind or water-splashed spores.
Prevention measures include:
Because it can spread by wind or water-splashed spores, take care to remove any infected plant material immediately. Avoid getting water on leaves as much as possible and decrease spray intervals during rainy periods.
A rose infected with black spot has round black spots with fringed margins on its leaves or stems. Yellow areas may develop around the spots and leaves may die or drop. This fungus requires water to germinate and infect plants, and can be spread by splashing water. It can survive on dead plant material.
Prevention measures include:
While botrytis can affect many plant parts, it usually damages tender tissues such as flower petals, buds, seedlings, and weakened or injured tissues. The infected plant material turns brown or black, and a gray fungal growth may appear.
It usually develops during prolonged, cool spells when temperatures fall below 60°F and the conditions are moist. The spores can spread rapidly by pruning equipment, and they can survive in decaying plant material and infested soil.
Prevention starts with good sanitation, including:
Other preventative measures include:
Inspect your plants for signs of infestations, including mites, thrips and aphids, and beetles and worms.
|Plant Type||Zone 1||Zone 1A||Zone 2||Zone 3||Zone 4|
|18"/24" Patio Tree||$0.74||$0.37||$0.95||$1.26||$1.42|
|36" Standard/Two-fer™ Tree||$1.16||$0.68||$1.31||$1.68||$2.00|
|Tops in Pots™||$1.31||$1.26||$1.42||$1.63||$2.05|
|Weeks Roses reserves the right to assess a fuel surcharge should conditions warrant.|
|Bush & Climber Description||Grade||Price Code||100-495||500-995||1,000-2,495||2,500-4,995||5,000-9,995||10,000+|
|B & C - Budded - Patented||#1||A||$8.95||$8.75||$8.55||$8.35||$8.05||$7.80|
|B & C - Budded - Patented||#1||B||$8.85||$8.55||$8.30||$8.05||$7.75||$7.50|
|B & C - Budded - Non-Patented||#1||C||$6.35||$6.10||$5.90||$5.60||$5.35||$5.10|
|B & C - Ownroot - Patented||#1||D||$6.55||$6.25||$6.00||$5.75||$5.45||$5.15|
|B & C - Ownroot - Non-Patented||#1||E||$5.75||$5.50||$5.20||$4.95||$4.65||$4.35|
|B & C - Ownroot - Miniatures||#1||P||$5.30||$5.00||$4.70||$4.45||$4.20||$3.85|
|B & C - Budded - Patented||#1.5||AA||$7.40||$7.15||$6.90||$6.70||$6.45||$6.25|
|B & C - Budded - Patented||#1.5||BB||$7.25||$6.95||$6.70||$6.45||$6.20||$6.00|
|B & C - Budded - Non-Patented||#1.5||CC||$5.25||$4.95||$4.70||$4.45||$4.20||$4.00|
|B & C - Ownroot - Patented||#1.5||DD||$5.25||$5.00||$4.80||$4.35||$4.15||$3.90|
|B & C - Ownroot - Non-Patented||#1.5||EE||$4.70||$4.40||$4.15||$3.95||$3.70||$3.50|
|B & C - Ownroot - Miniatures||#1.5||PP||$4.20||$4.00||$3.75||$3.40||$3.15||$2.90|
|Tree Description||Grade||Price Code||25-95||100-245||250-995||1,000+|
|Tree - 18" Miniature||#1||V||$12.10||$11.80||$11.50||$11.20|
|Tree - 36" Standard||#1||T||$17.00||$16.75||$16.50||$16.25|
|Tree - 36" Two-fers™||#1||R||$18.00||$17.80||$17.55||$17.30|
|Tree - 24" Patio||#1||W||$12.70||$12.40||$12.10||$11.75|