Nutrient Imbalances
A rose that has either too much or too little of any nutrient will suffer. Most of these nutrient imbalances can be diagnosed by using color photographs {See color chart of nutrient deficiencies at end of chapter.) There are 16 nutrients that roses need and thus there are 32 possible imbalances of nutrients, plus some other toxicity effects such as too much sodium.
Fortunately, there are only four of these imbalances that are frequently observed, and it is important that the Consulting Rosarian is aware of them. These are:
A rose that has either too much or too little of any nutrient will suffer. Most of these nutrient imbalances can be diagnosed by using color photographs {See color chart of nutrient deficiencies at end of chapter.) There are 16 nutrients that roses need and thus there are 32 possible imbalances of nutrients, plus some other toxicity effects such as too much sodium.
Fortunately, there are only four of these imbalances that are frequently observed, and it is important that the Consulting Rosarian is aware of them. These are:
- Nitrogen deficiency. Because nitrogen can leach from the soil (as nitrate), volatilize (as ammonia) or denitrificate (by bacteria), nitrogen needs to be constantly added to the soil. In roses lacking nitrogen, the leaves will show an overall pale yellow-green color, the plant will be stunted and stem size will be smaller than normal. This can be caused by a too high or too low a pH.
- Oxygen deficiency. This is a lack of air to the roots typically caused by over watering or poor drainage. The veins of the leaf will show chlorosis (yellowing) followed by interveinal chlorosis.
- Iron deficiency. The appearance of leaves on a plant suffering from iron deficiency has the opposite look of oxygen deficiency – the interveinal areas show chlorosis while the veins remain green. It is rare that iron is actually deficient in the soil, but rather it is likely that something is making the iron unavailable. Possible causes are high pH, poor aeration of the soil, high soluble salts or excessively high concentrations of manganese, zinc or phosphorus. Foliar sprays can give temporary relief if they contain iron. This may also be caused by too high or low of a pH.
- Leaf burn. he edges of the leaves turn brown and crispy. The fundamental cause of this is a lack of water getting to the edges of the leaves. This can be caused by anything that either makes water unavailable to the plant or excessively increases the water loss from the plant. Typical causes include over fertilizing with synthetic fertilizers, high salt level in the soil, lack of water, heat stress, spray burn or a combination of the above
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