S O U T H W E S T   R E P R I N T S

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Spotting Nutrient Deficiencies in Citrus Leaves

Excerpted from AZ1007, "Guide to Common Nutrient Deficiency and Herbicide Injury Symptoms in Citrus" at http://ag.arizona.edu/pubs/crops/az1007/az1007-1.html


NITROGEN
Leaves show general yellowing of foliage, beginning with older leaves and then appearing on younger leaf flush. Leaves become progressively more yellow, with no distinct pattern. In severe cases, leaves will senesce and foliage will become sparse. Nitrogen deficiency often occurs in winter or early spring because of low tree nitrogen reserves, low soil temperatures and/or lack of root activity.

May be confused with iron, manganese and/or zinc deficiencies. Nitrogen deficiency generally occurs on older leaves first, while the other deficiencies occur on younger foliage first. Nitrogen deficiency may also be confused with Princep (simazine) herbicide injury.


IRON
Leaves show yellowing of new leaves. In mild cases leaf veins may remain green (interveinal chlorosis). In severe cases leaves will become ivory-colored with no visible venation followed by leaf and twig abscission. Iron deficiency often appears in winter due to low soil temperatures, and root inactivity. High soil pH will cause iron deficiency, especially in trees on trifoliate or trifoliate hybrid rootstocks, such as 'Carrizo', 'Troyer', or 'Swingle'. Iron deficiency will also occur on poorly drained soils.

May be confused with nitrogen, manganese or zinc deficiencies. Iron deficiency symptoms occur on the younger leaves, whereas nitrogen deficiency symptoms occur on the older foliage. Interveinal chlorosis induced by manganese deficiency is less distinct than that caused by iron deficiency. Leaves of zinc-deficient trees exhibit chlorosis symptoms similar to that of iron, but are usually smaller.


MANGANESE
Leaves show interveinal chlorosis on the new foliage. Leaf size is normal. Veins appear green but are fuzzy or mottled; interveinal areas are yellow. Manganese deficiency often appears in winter due to low soil temperatures and root inactivity, but will disappear in the early spring. Only a persistent and severe pattern on the foliage needs correction.

May be confused with iron and zinc deficiencies. Unlike veins of iron deficient leaves, which are sharply delineated, those of manganese deficient leaves are fuzzy. Zinc-deficient leaves are usually smaller than normal, while manganese-deficient foliage is normal sized.


ZINC
New leaves are yellow, mottled and smaller than normal. When symptoms are mild, veins remain green, and interveinal areas are yellow or cream colored. When symptoms are severe, veins turn yellow, especially near the leaf tip. Small green dots in the yellowed area may appear. Necrosis (tissue browning and death) may occur beginning at the leaf tip and margins. Severely affected trees exhibit leaf and twig defoliation. Zinc deficiency is common on trees affected with Macrophylla decline.

May be confused with iron and manganese deficiency. Zinc-deficient leaves are generally smaller than leaves that have iron or manganese deficiency. Necrosis usually occurs only on zinc-deficient leaves.

Maricopa County Master Gardener Volunteer Information
Last Updated January 23, 2004
Author: Lucy K. Bradley, Extension Agent Urban Horticulture, University of Arizona Cooperative Extension, Maricopa County
© 1997 The University of Arizona, College of Agriculture and Life Sciences, Cooperative Extension in Maricopa County
Comments to Maricopa-hort@ag.arizona.edu 4341 E. Broadway Road, Phoenix, AZ 85040,
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