Home citrus tree growers run into a number of pest, bacterial and fungal problems. However, yellow leaves are a common condition that is the result of nitrogen or magnesium deficiency. It is essential to monitor your citrus tree for signs of leaves yellowing or defoliation. Routinely fertilise the tree to give it the proper nutrition. Provide the best nutrients for your tree to restore its health or to prevent yellow leaves.
Lack of Nitrogen
A citrus tree not getting enough nitrogen will exhibit signs of the problem on its oldest leaves. Leaves begin to fade from light green to yellow. Once the leaf has turned completely yellow, it will fall off the tree. A tree that has lost most of its canopy will see a reduction in its fruit production. To ensure a yearly fruit crop, it is essential to monitor your tree's leaves during the growing season.
Lack of Magnesium
Magnesium deficiency becomes evident at the base of leaf stems. Gardeners will notice yellow blotches on mature leaves that spread up the leaf and near the fruit. These splotches actually form a V-shaped pattern on the leaf. When the leaves have lost most of their colour, they become susceptible to falling from cold conditions or rain. The twigs that are missing most of their leaves begin to fall in the springtime. Twig loss will affect the mount of fruit that a citrus tree can produce.
Find out which nutrients your citrus tree is missing by conducting a soil pH test. You can purchase a soil-testing kit from your local county extension office. Dig a 6-inch hole in the planting location to collect samples. Dry out the samples by placing them in the sun. Take out any other organic matter, such as leaves or grass. Send the samples off to the laboratory's address provided on the testing kit. Wait a few weeks for the results. On the results, you will see what nutrients the tree is lacking to cause the yellowing of leaves.
Fixing Nitrogen Deficiency
Supply your tree with nitrogen throughout the growing year. Give your tree slow-release fertiliser with a NPK amount of 5-1-3. Spread the fertiliser around the base of the tree in the early spring when the ground has started to warm up. Water the area thoroughly after fertiliser application. Apply another round of fertiliser in six to eight weeks, according to the directions on the fertiliser's label. Discontinue fertilising the tree before the first frost, so the tree can go into dormancy and the new growth will not be harmed by winter conditions.
Fixing Magnesium Deficiency
Provide enough magnesium for your citrus tree. Spread Epsom salt around the base of the tree. Use roughly a couple of tablespoons to cover the area a few inches from the base of the tree. Do not allow the salt to touch the tree, and water thoroughly. Give your citrus trees Epsom salts every two to three months.