Identification Guide: Nutrient Deficiencies
| Nitrogen Deficiency
Nitrogen contributes primarily to green growth and is used most heavily when your plants are growing rapidly. The leaves of a nitrogen deficient rose show an over-all yellow or light green color. The older leaves are more affected than the newer growth because nitrogen is mobile within the plant and will move from the older foliage to newer leaves when in short supply. This older foliage may turn clear yellow and ultimately fall off. Slower growth, stunted plants and reduced stem length and diameter are also symptomatic of nitrogen deficiency. Flowers of the darker colored cultivars may appear several shades lighter than normal and the buds of any variety may fail to open.
Iron deficiency results in interveinal chlorosis of the younger foliage (yellow foliage, green veins). If the condition worsens the newly formed leaves may remain small and can become completely pale yellow to white. Iron deficiencies can be induced by high levels of manganese, zinc, or phosphorus. Iron deficiency symptoms with adequate iron present can also be caused by excessive salts, high pH, over watering, poor drainage and temperature extremes. In order to be identify and correct iron deficiency symptoms, these other environmental and cultural problems must be addressed.
Phosphorus is essential for good root growth and flower production. The first symptom of phosphorus deficiency is an overall stunting of the leaves and shoot growth. Later, the older leaves may lose their luster, becoming dull green, and drop off. Root development is reduced, which results in poor flower production and slow-to-open buds on weak stems. A slight purpling of the underside of the midrib can develop on some cultivars.
Potassium encourages root growth and vigor increasing your plants resistance to disease. Deficiency results in slow growth, shorter than normal weak flower stems and small short deformed flower buds. Tip and marginal leaf burn beginning with the older leaves. Potassium deficiency may contribute to the production of "blind shoots" (new stems with no flower).
Calcium deficiency causes abnormal root growth causing the tips to shorten, get brittle and eventually die. Young leaves are distorted, older foliage become dull green and may curl down at the margins. Calcium deficiency can also contribute to weak stems and in the cut flower industry is associated with a condition known as black tip on some red rose varieties. There is a relationship between calcium and boron for normal growth. If calcium levels are high the relative boron levels must also be high for boron deficiency symptoms not to occur.
Magnesium is essential for photosynthesis. Deficiency can cause stunting and yellowing between the veins on the foliage (AKA interveinal chlorosis). These symptoms show up on the older foliage first because magnesium, like nitrogen is mobile within the plant. This yellowing can eventually cause purplish or brown dead spots that can eventually cover the entire leaf.
Sulfur deficiency causes young leaves to develop light green to yellowish in color. Plants may be spindly and smaller than normal.
Boron deficiency can cause small, thickened, curled, scorched leaves and death to the terminal bud. Death of the terminal bud causes lateral buds to develop contributing to witches broom effect. Boron deficiency can cause "bullheads" (flowers with shortened petals, that are abnormally thick and have the margins roll in).
Chlorine deficiency can cause malformed wilted foliage, followed by chlorosis. It's believed that an adequate supply of chlorine increases disease resistance.
Copper deficiency symptoms include distorted young leaves with yellow tips. Ultimately the growing point dies, and short, stunted, lateral shoots develop.
Molybdenum deficiency can cause stunting and lack of vigor. It can also cause malformed leaves with marginal scorching and cupping. Molybdenum is used in very small amounts and can be toxic if over applied. Molybdenum deficiencies can be corrected with only a few ounces applied per acre.
Zinc deficiency symptoms are similar to those caused by copper deficiency. However, zinc deficiency can also the lateral shoots that develop after the terminal bud dies to stunt causing "little leaf" symptoms.
Soil compaction commonly occurs in heavier soils. Compaction problems are quickly created when soil is subjected to heavy traffic, or physically worked in wet conditions. Compaction can also occur over time with normal day to day activities like foot traffic and irrigation. Soil compaction creates several problems which prevent healthy vigorous roses. Roots have a difficult time penetrating compacted soil, and water does not move freely through it. Compacted soil impedes free gas exchange between the soil and the air above and the absorption of essential minerals and water may decrease. Roses may become more susceptible to disease in compacted soil. As a result, roses may become stunted or show a decreased rate of growth.