Orange tree deficiencies, particularly those dealing with dangerously low levels of essential nutrients, can cause severe illness in these citrus plants. Identify the more prevalent deficiencies that appear in orange trees, the associated symptoms and damage and solution methods to bring your orange trees back to health. Always grow vigorous trees through proper maintenance for greater healing ability.
Orange trees are citrus plants that require full sun exposure for proper growth. Grow orange trees in soil with a pH of 6 to 8, according to the AgriLife Extension Texas A&M System. Drainage is of the utmost importance with orange trees because waterlogged soil and standing water interferes with the tree's ability to absorb vital nutrients and water; taking up water quickly, the tree becomes over-filled with water and fruit crops are easily destroyed. If soil has drainage problems, amend the soil with organic matter like compost for improved water flow.
Types of Deficiences
Often contributed to poor soil conditions or excessive fertilization, certain nutrient contents become depleted and affect the health of your orange trees. The most widely noticed deficiency is an absence of zinc. A zinc deficiency is sometimes known by a particular name, as in Florida, where it is referred to as "rosette", according to the University of Florida IFAS Extension. Other highly common deficiencies include low levels of manganese and iron.
Symptoms and Damage
Zinc deficiencies in orange trees cause abnormal green stripes to form on leaves while the rest of the leaf fades to a yellow/white hue, according to the University of Florida IFAS Extension. Leaves may also appear smaller and take on an upright habit. Fruit set reduces and the orange fruit becomes smaller with a very low moisture content. Deficiencies of iron are referred to as iron chlorosis. Symptoms include leaf tissue faded to a whitish color except for veins which remain green. From one branch to the entire tree, different levels of severity cause branch dieback and smaller fruit size. Manganese deficiencies on orange trees causes leaves with green veins but the leaf tissue between veins substantially fades; leaf size is consistent but discoloration may progress to brown and leaves often drop early.
Things to Avoid
Avoid overuse of poultry manure or chemical fertilizers as too much phosphorus or nitrogen can result in depleted zinc counts, according to the University of Florida IFAS Extension. Additionally, extremely acid or alkaline soil may lead to problems. High alkalinity causes loss of iron and manganese. Avoid over-irrigating your soil as this may lead to waterlogged soil. Do not plant trees in regions that experience freezing conditions and cold soil as injury may occur. If a freeze occurs, however, cover the top of your orange tree with plastic or a blanket; though the cover does not need to encompass the entire tree all the way to ground level, securing it is essential in preventing the cover from blowing away in windy conditions, according to the AgriLife Extension Texas A&M System.
To fix a zinc deficiency, apply a zinc solution like zinc sulfate with up to 4 lbs of elemental zinc per acre, according to the University of Florida IFAS Extension. Application of spray to foliage is best when completed when leaves have reached 66 to 100 percent growth. For iron problems, sprays are not very effective on foliage; consider use of chelates like Fe-EDTA that are applied to orange trees' soil. With manganese problems, manganese foliar sprays bring the nutrient levels back up; look for a manganese solution with 2 to 3 lbs of elemental manganese for every acre.