A Lot Of Rose Problems Are Caused By Various Forms Of MALNUTRITION. Here is What To Look For.
by Bob Bauer
The new leaves and shoots on your roses appear as light yellow green to white with darker green veins showing. This is the most common and apparent deficiency to occur in roses. Photosynthesis needs iron in order to work. If there is no iron there is no chlorophyll, hence the rose leaves cannot turn green. This is most commonly caused by clay soils. Certain kinds of clay (clays are a group of several different minerals) 'eat' iron as they go about the process of chemical weathering.
Treatment: This condition necessitates the addition of chelated iron to the soil on a regular basis. Just a handful around the base of the plant out to about 1 foot in radius is enough to start fix the problem usually. There are some iron additives that include nitrogen fertilizers with them, so that you can kill two birds with one stone.
Rose Problems Page
Leaves are pale and yellow in the center with dead areas close to the middle of the leaf. Oldest leaves are the first affected. Leaves fall off the plant early.
Treatment: Add a fertilizer containing Magnesium.
Young leaves appear to be small and pale green. Veins are a lighter yellow color. Rusty red spots sometimes develop in the center of the leaves. Stems appear small and short. The overall rose becomes stunted or even defoliated. This is caused by the rose using up all of the available nitrogen in the soil, or by the breakdown of too much wood or bark mulch or fall leaves. Balancing your mulch with grass clippings can help you with this situation.
Treatment: Add fertilizer. But not just a 'Nitrogen only' lawn fertilizer, use a well balanced fertilizer with an NPK ratio of about 1:2:1. Rosesshort in Nitrogen are most likely to also be short in other nutrients as well.
'Will Scarlet'
Mature leaves stay green, but develop brown dead brittle edges. Young new leaves are red and don't turn green. Flowers develop but they appear small. Potassium is the nutrient that is the K of 'NPK' fertilizers. It is the third number on the list of say a label that reads: 10:20:10 for example. K is the chemical symbol for the element Potassium. Potassium shortage is a condition that is common in soils that are sandy.
Treatment: Apply a compound fertilizer that contains potassium or 'K'.
'Soleil d'Or'
Young leaves grow small and are very dark green. Purplish tints on the underside of the leaves near the center. The leaves fall off of the plant early. The plant will not bloom. Stems are weak and small. The bush appears stunted and will not get bigger.
Treatment: Apply a compound (NPK) fertilizer. Make sure that it is high in P (Phosphates).
The oldest leaves on the plant will get yellowish bands between the veins. While the veins remain green. This condition usually occurs when people are trying to raise the pH of their soil and add too much lime to the soil. Thus over doing it.
Treatment: Avoid over liming. If the symptoms persist there are manganese additives at the garden store.
Herbicide Damage: Leaves become narrow and twisted. Stems become reddish and distorted.
Treatment: Never spray herbicides (lawn weedkillers for example) on a windy day. Be carful in how you apply any herbicide. Cut off all affected canes and leaves and the rose should recover unless it was directly covered with the herbicide. If you want my advice: I believe that there is NO LEGITIMATE USE for herbicides in the garden. It usually boils down to just a matter of convenience for the gardener. There are other ways to deal with all of these problems with just a little thought and work.
Pesticide Damage: Purple or rust colored spots appear on the leaves in quantity. This can be caused not just by application of too much pesticide but also spraying the pesticides in conditions where the temperature is too hot or the humidity is too low.
Treatment: Closely read and follow ALL labels included with pesticides. This isn't just for the health of your roses, but for your own health. Remember that pesticides are meant to KILL various forms of life. That is their purpose. Never forget this.
Affected leaves are crinkled and torn at the edges. The edges die and turn brittle and brown. In severe cases the leaves turn yellow then brown and die and fall off. The buds also shrivel up and die, even though they will remain on the plant until pruned off.
Treatment: Nothing to do but say 'Uh oh.... looks like the end of the season". OR "Damn. I guess I pruned too early!" Or "The weather around here sure is unpredictable!"