Image |
Problem |
Description |
Solution |
|
Yellow Leaves |
Leaves turn yellow and may fall off. Could be caused
by poor drainage. |
Bad weather can slow chlorophyll production, so wait
it out. Add sand to improve drainage. |
|
Chlorosis |
Usually not a serious problem, caused by a lack of
iron, nitrogen, manganese or magnesium, or a salt build up. |
Add chelated iron to the soil, or in severe cases,
spray iron sulfate on the foliage. Apply a solution of epsom salts and water to the soil during the season. |
|
Aphids |
Aphids are very small insects, usually black or green,
mostly on the underside of leaves or on new growth. |
Thoroughly hose aphids off foliage; you can also apply
insecticidal soaps to control aphids. A more natural way to keep this pesty instect off your roses would be to buy a bag of Lady Birds. |
|
Inadequate sunlight |
Leggy growth with no flower buds. |
Plant roses where they will receive 4 to 6 house of
direct sunlight a day. |
|
Leaf Cutter Bees |
Circles or ovals neatly cut out of the leaves, wilted
stems indicate tunnels inside. |
Seal canes with white glue (Elmers® Glue works just
fine) after pruning to prevent the insects from tunneling the stems. |
|
Japanese Beetles & Rose Chafers |
Beetles that eat various parts of the rose plant. |
Pick the insects off individually, or use a biological control called "milky spore disease", which is commercially available. There are other means of prevention: Safer® Japanese Bettle Traps that work using a pheromone are pretty good; but remember place these traps AWAY from your roses. |
|
Rose Borers |
These creatures enter the cane and feed on the pith
inside. Canes will turn black and wilt. |
Use a multipurpose spray to get rid of the fly that
lays eggs; seal canes after pruning to prevent further borer entry. |
|
Thrips
White or tan |
Buds turn brown and do not open, or are distorted.
Thrips feed on plant juices. To
check, tap your rose bud over a paper towel (a darker material would work
better) check for moving hyphens. |
Control with a dust or spray. Direct spray into
opening buds. |
|
Spider Mites |
Leaves turn yellow, dry out, and in severe cases, fall
off the plant |
Hose the undersides of leaves with a fine spray of
water for 3 days in a row to disrupt the breeding cycle. An insecticidal soap will also
work well. |
|
Black Spot |
Leaves have black spots, and will fall off if fungus
is not treated. |
Pick off isolated leaves; control with spray or dust.
Provide good air circulation and allow foliage to dry. |
|
Stem Cankers |
Cankers may take various forms, depending on the
causal fungus, but are usually brown, reddish-brown, or black. Several cankers develop
cracks in which small black dots may be observed (these are fruiting bodies of the
fungus). When stems are girdled, the foliage turns yellow, wilts and dies. When severe, the plant is killed. |
For control, start with disease-free plants. Prune and
destroy cankered canes, sterilizing pruning tools between cuts. Keep plants in healthy
condition. Spray as for black spot control. Protect plants during the winter. Varieties differ in susceptibility. |
|
Canker Dieback |
Rose canes turn dark brown or black and die
progressively down the stem. |
Always remove the damaged part of the cane, then
follow a regular spray or dust program. Avoid injury to canes, and use a sealer after
pruning. |
|
Crown Gall |
These are tumor-like swellings appearing near the bud
union; plants lose vigor and die. |
Cut off galls with a sharp knife, disinfect with
alcohol. Paint pruned area with mild bleach solution. Burn diseased portions of the plant. |
|
Mildew |
Greyish/white patches on leaves, flower buds and young
shoots. Appears most often when days are cool, and the air circulation poor. The leaves will curl and become distorted in sever cases. |
Any commercial Fungicide should take care of this
problem. |
|
Rose Midge |
Mosquito-like in shape and they are 1-2 mm in length.
The tiny rose midge larvae feed on the tender new growth and immature buds and what they do not eat, turns black and withers. This type of damage can be confused very easily with foliar burn caused by some pesticides. |
According to the literature repeated applications of Diazinon® to infested soil as well as a foliar spray gave excellent control to field grown roses (Smith and Webb, 1976. The Rose Midge 1976 ARS Rose Annual pp 57-73). |
|
Rose Slugs/Sawflies |
Roseslugs are the immature stages of primitive wasps
called sawflies. Roseslugs look more like caterpillars than slugs. They are not slimy and do not have rasping mouthparts like true slugs. Roseslugs differ from caterpillars in that their abdominal legs do not have hooklike crochets to cling on to foliage or twigs. |
Rose slugs look like caterpillars but they are not,
consequently some insecticides such as Bacillus thuringiensis will not kill them. If there are only a few rose bushes infested with the roseslugs, pull the leaves off and kill any larvae found on the upper or lower surfaces of the leaves. If the damage is widespread to many rose bushes, chemical control should be considered. Any contact or systemic insecticide labeled for use on roses will kill the roseslugs. The key thing is to spray thoroughly to make sure that the spray covers the upper and lower leaf surfaces. Also, spray the soil under the rose bushes as the larvae pupate in the soil prior to overwintering. |
|
Earwigs |
Earwigs like to eat the stamens, the little stalks on which the pollen producing anthers are positioned. They are not above eating a hole in the petals or leaves too, just for spite. |
Control of earwigs is not easy. Baits are available that contain carbaryl, the active ingredient in Sevin®, and these are reasonably effective. Barrier sprays of long residual insecticides such as chlorpyriphos (Dursban®) help keep earwigs out of the house and roses. Treating under pots and behind woodpiles, flowerboxes, etc. with an insecticide helps control earwigs as well. Organically minded gardeners have been using rolled newspaper to trap earwigs during the night, then placing said newspaper, with earwigs, into a tightly sealed trash cans in the sun to die a horrible death, or thrown into a freezer to die a kinder, gentler death. The earwigs may also be downed in soapy water or beer, depending on your fancy. They may also be trapped in lowsided cans (tuna, catfood, tec.) to which a half an inch of vegetale oil has been added. |
|
Gophers |
They eat rose roots, often killing the plant. |
The best solution would be to plant in containers.The
ideal container for this use is called a "Squat." Squats are lower and wider
("squattier") than the usual sort of nursery pot; this configuration allows a rose to form a sizable root ball, with lots of the essential feeder roots. For a full-sized plant, use 15-Gallon squats, which have sturdy, molded-in handles. You may want to add about 8-10 more 3/4 inch holes for added drainage. |