I-Fungal diseases:
1- Anthracnose:

The causal organism:             colletotrichum gloeosporioides

Symptoms:

Black circular spots up to one-half inch appear on fruit. The center of the spots may be slightly sunken and spots may develop cracks. During moist periods, the spots produce pinkish, moist masses of fungal spores. As the fruit ripens, the infection spreads rapidly into the flesh causing a greenish-black, fairly firm decay. Fungicides can control the disease and should be applied at bud swell

Polyram D-F 250 / 100 L.W
or Bellis 50G / 100 L.W
or Amistar 40 cm / 100 L.W

2-Cotton root rot

The causal organism:             Phymatotrichopsis omnivora

Disease symptoms
Although avocado is susceptible to cotton rot root, it is not a common diseases. It is characterized by a sudden wilt of the tree. That leaves turn brown and remain on the tree. Very young trees tend to become diseases, rather than old ones. The only control is to avoid planting trees in soil known to be infested with the fungus.

Control
Use one of the following activein grediant at any fungiadiant : Metalaxyl - Mancozeb

3-Phytophthora root rot:

The causal organism             Phytopphthora cinnamomi

Symptoms:

Infected trees have small leaves which are lighter green in color than healthy leaves wilt and drop, eventually leading to complete defoliation of the tree. Twigs and branches die back. There is a light fruit set with small fruit. The fungus infects roots up to one-quarter inch in size, although it is the feeder roots that are primarily affected. These roots become blackened and brittle before they die.

The disease occurs if the pathogen is present in soil and if there is excessive soil moisture. Poor drainage can be a contributing factor to disease development. The fungus can be introduced to new areas by movement of infected nursery stock or infested soil. Soil on implements can also serve as a means for introduction of the fungus to non-infested areas. Fungicides should be used in combination with sanitation in the nursery and maintaining adequate drainage in the field.
Control
Use one of the following activein grediant at any fungiadiant : Metalaxyl - Mancozeb

4-Scab:
The causal organism             Sphaceloma perseae

Symptoms

Circular, brown, scabby areas are found on mature fruit. Leaves have brown spots and become crinkled. The disease can become a problem if there is cool, moist weather when fruit and leaf tissue is young. Fungicides can control the disease and should be applied when flower buds appear, near the end of the main bloom period, and 3-4 weeks after that

Control

Polyram D - F 200 G / 100 L.W

5-Seedling blight.

The causal organism             Phytophthora spp

Symptoms

This can be an important disease in nursery production. Leaves show irregular reddish-brown areas that enlarge along the larger veins. The disease is favored by periods of heavy rainfall and high humidity, when seedlings are young and succulent. The following cultural practices can prevent or minimize damage. Plants should be grown on benches. The use of soil should be avoided to prevent introduction of the pathogen. Irrigation water provides a less-favorable microclimate for disease development. Fungicides should be used only in combination with cultural control practices

Control

Use one of the following activein grediant at any fungiadiant : Metalaxyl - Mancozeb

6- Wood rot:

The causal organism:             Ganoderma lucidum

Disease symptoms

This fungus contributed to the gradual decline and death of trees in a portion of an orchard in the Rio Grand Valley. The decline occurred over a period of several months during the summer. The leaves of affected trees first turned pale to yellow and trees soon lost leaves. Eventually, trees were completely defoliated and died. Fruiting bodies of the fungus were found on dead and dying trees. The above-ground symptoms of the disease resemble Phytopthora root rot .The disease in a portion of the orchard with poor drainage that was subject to water logging. The water logging led to the death of feeder roots (again, a symptom that resembles Phytophthora root rot) and stressed the trees. This environmental stress allowed the fungus to develop within trees. The fungus infected the trees via wind-blown spores that entered the tree through wounds. There is no chemical control for this pathogen. Encouraging vigorous tree growth by minimizing environmental stresses (e.g. improving soil drainage) will prevent establishment of the fungus in the tree

Control

Use one of the following activein grediant at any fungiadiant : Metalaxyl - Mancozeb