Grapefruit Tree Leaves Falling Off Mesa AZ
The Asian Citrus Leaf Miner
Tree Disease Basics playlist
Whiteflies in Temp AZ
Gummosis, (Phytophthora) is a water mold (Class Oomycetes, formerly a fungus-like protist) that is found throughout the world. Under favorable conditions (high moisture and temperature) it produces large numbers of motile zoospores that can swim in water for short distances. These zoospores are the infective agents that may be transported in rain or irrigation to the roots. When zoospores contact roots they encyst, germinate and enter the root tip resulting in rot of the entire rootlet.
Foot rot or gummosis occur when zoospores splash onto a wound or bark crack around the base of the trunk. Additionally, there is an association of Phytophthora root rot when roots are damaged by citrus root weevils, particularly Diaprepes abbreviatus. Root stock susceptibility depends on which Phytophthora species are present and the presence of favorable soil, water and environmental conditions.
The symptoms are leaf - yellow foliage and shoot die-back. If citrus weevils are present adults may feed on leaves causing notching. And- reduced fruit size and yield.
Trunk infection of the trunk by Phytophthora results in dark water soaked areas in the area of active infection. Lesions usually occur on the bark or at the bud union. Lesions may exude copious amount of gum and a brown necrotic area will be found under the bark lesions. Dead bark tends to break away from the trunk in vertical strips. Lesions may spread around the circumference of the trunk slowly girdling the tree.
Phytophthora may result in poor tree health, thin canopy, failure to make new growth, and little water and nutrient uptake leading to wilting. When roots are infected the surface of the root becomes soft, discolored and appears water-soaked. Fibrous roots slough their cortex leaving only the white thread-like root cylinder.
It should be noted that: Phytophthora root rot symptoms progress much more rapidly in the presence of the citrus root weevil.
Most scion cultivars are susceptible to bark infection, while most root stocks are moderately tolerant to bark infection. In ascending order, Cleopatra mandarin, Sour orange, rough lemon, Rangpur lime, Carrizo, Troyer are tolerant to root rot. Trifoliate, Swingle citrumelo, Yuman and alemow are considered highly resistant to bark infection and tolerant to root rot. Swingle citrumelo is the most tolerant rootstock. The presence of Diaprepes root weevils, Phytophthora palmivora and poorly drained soil can render normally tolerant Swingle citrimelo and Carrizo suseptible to Phytophthora root rot infection.
The Ash Whitefly is even more dangerous to the health of your trees then Gummosis,
Arriving here in 2011 and breeding up to 15 times a year, the Asian Citrus Leaf Miner was in every citrus tree I looked at for several years.
The population grew unchecked well into the summer of 2019,. So for at least 8 years, the leaves on your citrus trees have been producing far less energy than normal.
Because of this the reserve cells are dangerously low. Biologically speaking, your citrus trees have run out of gas.
Because it has no natural predator in Arizona there was nothing to keep it in check. However now it competes with the Ash Whitefly.
It takes years but eventually a citrus trees reserves will be drained to the point that it can no longer defend itself against any insects or soil born fungus.
That’s where we come in, if it’s not too late we can get you started on a program to restore the energy reserves of your trees.
Watch the videos on this page to learn more.