Melanose is a fungus seen on young citrus fruit, mainly affecting grapefruit. The scabbed fruit rind doesn’t reduce fruit quality, though, it is unattractive. The disease is typically more serious in trees that are ten years or older. As the fungus spreads in dead wood, swift pruning is an efficient way of fighting this disease. Also, Liquid Copper Fungicide can be applied.
Root Rot (Collar Rot or Brown rot) is a tree disease due to soil-inhabiting fungus.
Symptoms are dark brown patches of hardening bark on the tree’s trunk. It is normal for ooze to seep from the infected areas. Over time, as the disease spreads, the bark cracks dry out and die. All that is left is a dark sunken canker. Also, the condition can create decaying and browning on the fruit as well as die-back and yellowing on the foliage. This fungus inhabits the soil and is most predominant during periods of excessive rain and in wet soil.
To control root rot, it is vital to get rid of all damaged fruit and leaves when it falls to the ground. You can also prune all the lower branches, so they are over two feet off the ground. Some fungicides that can be used to regulate root rot is Captan and Agri-Fos.
Aphids do small damage to a tree. However, under the right conditions, the aphid population can increase very quickly and create severe damage to a citrus tree.
Aphids damage the tree by sucking the sap out of the leaves. The symptoms are quite clear on the leaves in the form of yellowing and the twisting of the leaves and numerous puckered marks which looks like warped leaves. As the gravity of the aphid infestation rises, twig and branch dieback and leaf drop are apparent.
Aphids can be controlled using safer, newer insecticides instead of hazardous older chemicals. For significant outbreaks dose the tree with Trounce. The spray should be applied all over the leaves and other areas of evident insect concentrations and feedings. If dealing with this tree diseases and insects creep you out, schedule an appointment with a tree care company to do it for you.