Grapevine, Apple and Peach Diseases | Diseases of Field & Horticultural Crops & Their Management-II

Unit-III

Syllabus
Fruits crops:
Mango: anthracnose, malformation, bacterial blight, and powdery mildew;
Citrus: canker and gummosis;
Grapevine: downy mildew, Powdery mildew;
Apple: scab, powdery mildew, and crown gall;
Peach: leaf curl.

Part - B

Grapevine

1. Downy Mildew:

Downy mildew is a fungal disease that affects grapevines, caused by the pathogen Plasmopara viticola. Because the disease is prevalent in areas with high humidity and moderate temperatures, grapevine growers face a significant problem. The symptoms of downy mildew in grapevines include the appearance of yellow spots on the upper surface of the leaves, which are accompanied by downy growth on the lower surface of the leaves. Over time, the leaves can become distorted and defoliation can occur, leading to significant yield losses.

Several practises can be used to control downy mildew in grapevines:

• Cultural Control: Cultural control methods include removing infected plant material, pruning the vines to improve air circulation, and managing irrigation to reduce humidity levels.
• Chemical Control: Fungicides containing copper, mancozeb, and cyazofamid can be used to control downy mildew in grapevines. It is important to note that regular monitoring and timely application of fungicides are critical for effective management of downy mildew.
• Biological Control: Biological control methods involving the use of beneficial microorganisms such as Bacillus subtilis and Trichoderma harzianum can also help to suppress the growth and spread of the downy mildew pathogen.
• Integrated Disease Management (IDM): A combination of the above control methods can be used as an integrated disease management strategy to manage downy mildew in grapevines.

1. Powdery Mildew:

Powdery mildew is a fungal disease that affects grapevines, caused by the pathogen Uncinula necator. The disease is prevalent in areas with moderate temperatures and high humidity, making it a significant problem for grapevine growers. The symptoms of powdery mildew in grapevines include the appearance of a white, powdery coating on the leaves, shoots, and fruit of the vine. Over time, the leaves can become distorted, and defoliation can occur, leading to significant yield losses.

To manage powdery mildew in grapevines, several practices can be employed:

• Cultural Control: Cultural control methods include removing infected plant material, pruning the vines to improve air circulation, and managing irrigation to reduce humidity levels.
• Chemical Control: Fungicides containing sulfur, triadimefon, and tebuconazole can be used to control powdery mildew in grapevines. It is important to note that regular monitoring and timely application of fungicides are critical for the effective management of powdery mildew.
• Biological Control: Biological control methods involving the use of beneficial microorganisms such as Bacillus subtilis and Trichoderma harzianum can also help to suppress the growth and spread of the powdery mildew pathogen.
• Integrated Disease Management (IDM): A combination of the above control methods can be used as an integrated disease management strategy to manage powdery mildew in grapevines.

It is important to note that prevention is key when it comes to managing both downy mildew and powdery mildew in grapevines. Farmers should practice good vineyard hygiene by removing infected plant material, using disease-free planting material, and maintaining proper irrigation and ventilation to create an environment that is less favourable for the growth and spread of these diseases.

Apple

1. Apple Scab:

The pathogen Venturia inaequalis causes apple scab, a fungal disease. The disease affects the leaves, fruit, and shoots of apple trees, and it can cause significant yield losses if left untreated. The symptoms of apple scab in apple trees include circular, olive-green or brownish-black spots on the leaves, which can cause defoliation. The fruit can also be affected, with scab-like lesions that can cause deformities and cracking.

To manage apple scab in apple trees, several practices can be employed:

• Cultural Control: Cultural control methods include removing infected plant material, pruning the trees to improve air circulation, and managing irrigation to reduce humidity levels.
• Chemical Control: Fungicides containing captan, myclobutanil, and pyraclostrobin can be used to control apple scab in apple trees. It is important to note that regular monitoring and timely application of fungicides are critical for the effective management of apple scab.
• Biological Control: Biological control methods involving the use of beneficial microorganisms such as Bacillus subtilis and Trichoderma harzianum can also help to suppress the growth and spread of the apple scab pathogen.
• Integrated Disease Management (IDM): A combination of the above control methods can be used as an integrated disease management strategy to manage apple scab in apple trees.

1. Powdery Mildew:

Powdery mildew is a fungal disease caused by the pathogen Podosphaera leucotricha. The disease affects the leaves, shoots, and fruit of apple trees, and it can cause significant yield losses if left untreated. The symptoms of powdery mildew in apple trees include the appearance of a white, powdery coating on the leaves, shoots, and fruit of the tree. Over time, the leaves can become distorted and defoliation can occur, leading to significant yield losses.

To manage powdery mildew in apple trees, several practices can be employed:

• Cultural Control: Cultural control methods include removing infected plant material, pruning the trees to improve air circulation, and managing irrigation to reduce humidity levels.
• Chemical Control: Fungicides containing sulfur, myclobutanil, and propiconazole can be used to control powdery mildew in apple trees. It is important to note that regular monitoring and timely application of fungicides are critical for the effective management of powdery mildew.
• Biological Control: Biological control methods involving the use of beneficial microorganisms such as Bacillus subtilis and Trichoderma harzianum can also help to suppress the growth and spread of the powdery mildew pathogen.
• Integrated Disease Management (IDM): A combination of the above control methods can be used as an integrated disease management strategy to manage powdery mildew in apple trees.

It is important to note that prevention is key when it comes to managing both apple scab and powdery mildew in apple trees. Farmers should practice good orchard hygiene by removing infected plant material, using disease-free planting material, and maintaining proper irrigation and ventilation to create an environment that is less favourable for the growth and spread of these diseases.

1. Crown Gall in Apple Trees:

Crown gall is a bacterial disease caused by the pathogen Agrobacterium tumefaciens. The disease can infect apple trees through wounds or natural openings, and it can cause significant damage to the tree if left untreated. The symptoms of crown gall in apple trees include the formation of rough, woody galls on the trunk or roots of the tree. These galls can interfere with the tree's ability to transport water and nutrients, leading to stunted growth and reduced yield.

To manage crown gall in apple trees, several practices can be employed:

• Prevention: Prevention is key when it comes to managing crown gall in apple trees. Farmers should practice good orchard hygiene by using disease-free planting material, avoiding wounding the tree during pruning, and minimizing soil disturbance.
• Chemical Control: Antibiotics such as streptomycin and tetracycline can be used to control crown gall in apple trees. These antibiotics are most effective when applied as a preventive measure before the infection occurs.
• Biological Control: Biological control methods involving the use of beneficial microorganisms such as Bacillus subtilis and Trichoderma harzianum can also help to suppress the growth and spread of the crown gall pathogen.
• Integrated Disease Management (IDM): A combination of the above control methods can be used as an integrated disease management strategy to manage crown gall in apple trees.

Peach

1. Leaf Curl in Peach Trees:

Leaf curl is a fungal disease caused by the pathogen Taphrina deformans. The disease affects the leaves, fruit, and shoots of peach trees, and it can cause significant yield losses if left untreated. The symptoms of leaf curl in peach trees include the curling, reddening, and distortion of the leaves. Over time, the leaves can become brittle and fall off, leading to defoliation and reduced yield.

To manage leaf curl in peach trees, several practices can be employed:

• Cultural Control: Cultural control methods include removing infected plant material, pruning the trees to improve air circulation, and managing irrigation to reduce humidity levels.
• Chemical Control: Fungicides containing copper, myclobutanil, and propiconazole can be used to control leaf curls in peach trees. It is important to note that regular monitoring and timely application of fungicides are critical for the effective management of leaf curl.
• Biological Control: Biological control methods involving the use of beneficial microorganisms such as Bacillus subtilis and Trichoderma harzianum can also help to suppress the growth and spread of the leaf curl pathogen.
• Integrated Disease Management (IDM): A combination of the above control methods can be used as an integrated disease management strategy to manage leaf curls in peach trees.

It is important to note that prevention is key when it comes to managing both crown gall in apple trees and leaf curl in peach trees. Farmers should practice good orchard hygiene by removing infected plant material, using disease-free planting material, and maintaining proper irrigation and ventilation to create an environment that is less favourable for the growth and spread of these diseases.