FRUIT PLANTS DISEASES-SYMPTOMS & CONTROL
Every year the home fruit plant grower has to face the menace of the various plant diseases, which invariably, with the onset of summers attack the plants, which if not controlled in time can play havoc. It is very important the grower to observe the disease symptoms and take necessary remedial actions. Given below are some of the common fruit plant diseases and their antidotes.
MANGO (49 plants per acre)
Powdery Mildew - A whitish powdery growth appears on the floral axis. The floral parts show become brownish, dry and fall off. Small fruits also drop because of the mildew attack on the panicle and branches of the floral axis. Eventually they also dry up and fall off leaving the main axis naked.
To control this disease apply a spray of 01 % Karathane 500ml in 500 liter of water (10ml per plant in 10 Liter of water) or Wet table Sulphur 1.25 kg in 500 ml water per acre (0.025 gm per plant in 10 Liter of water), once before flowering and again during flowering. A third application may be necessary after 10-15 days.
Anthracnose or Dieback – Dark brown to brownish black spots on the leaves, withering of the shoots and sometimes the small fruits also show raised dark brown or black areas.
To control this it is recommended to prune the shoots and the branches showing this symptom and burn them.
GRAPES (220 vines per acre)
Anthracnose or Dieback – Small light brown spots appear on the young leaves, which later grow in size, turn dark brown which later show up as holes in the leaves. In severe attacks early defoliation occurs. It some times leads to the new shoots to die tip backwards. It sometimes also affects the berries, which show dark brown depressed spots.
To control this prune the shoots during January-February and give one dormant spray of Bordeaux mixture (2:2:250) after pruning in 125 liter water per acre (.05 Liter of water per vine). Again spray this mixture during the last week of March. Spray Bavistin 50 WP 400 gm in 400 liter water per acre (2 gm Bavistin 50 WP in 2 Liter water per vine) during the last week of April. The Bordeaux mixture spray in 400 liter water per acre (2 gm in 2 Liter water per vine) is to be again repeated during last week of May and mid August. The Bavistin 50 WP 400 gm in 400 liter water is also to be repeated in mid July and first week of September.
Cercospora leaf spot – Small areas on the leaves become straw coloured with reddish centers and reddish brown margins.
To control this spray either the Bordeaux mixture or Bavistin 50 WP as suggested above for anthracnose.
Downy mildew – Light yellow oily spots appear on the upper surface of the leaves. These spots on the lower surface are covered with white downy growth of pathogen. Later these spots turn brown and brittle. The leaves dry up and fall. This disease is noticed in March – April and is most active in August after the rainy season. It also affects the growth of fresh shoots and tendrils.
Control is the same as in case of Anthracnose. However, one additional spray of Bordeaux mixture (2:2:250) in 400 liter water per acre (2 gm in 2Liter of water per vine) is recommended in mid September.
Powdery mildew – White powdery growth of fungus is observed on the leaves, tender branches and berries. The affected shoots turn black, the blossoms and berries fall off.
To control spray the vines with 0.25 Wet tables Sulphur 1.25 Kg in 500 liter water per acre (0.005 gm in 2 Liter water per vine).
Black or Blue rot mold - The berries are attacked while still on the vine. This is a result of attack by the wasps which injure them releasing the juice which then becomes the medium for the growth of fungus. The rupturing of the berries due to heavy growth sometimes also causes it.
To control spray insect repelling pesticides like Endosulfan 35 EC (Thiodan) 350 ml in 250 liter water per acre (1.5 ml in 1 Liter water per vine). In case of heavy growth thinning can be adopted.
Water berry – Due to water stress the berries dry up at the tip. Some times in May and June they appear to be half filled.
To control apply frequent irrigations during May and June. Thinning of over bearing vines can also be adopted.
PEARS (72 Plants per acre)
Pear scab - Olive dark moldy spots appear on the underside of the leaves. They later turn gray>. Similar spots sometimes also grow on the petals. The affected flowers and the petals dry up ands fall off. These spots may also appear on the fruit, which grow in size and crack.
To control spray 0.2 % Captan starting from the dormant stage to the petal fall stage at 10 days intervals. Seven to eight sprays may be necessary in case the disease persists. It is also recommended to collect the fallen leaves and burn them so that the infection does continue. In case of heavy vegetation pruning can also be adopted.
Shoot fruit blight – Small circular brown spots appear around a leaf scar or superficial wound on the bark of the plants. As they grow in size the centers become sunken and the edges raised above the surrounding healthy bark. The fungus grows in these spots.
To control remove the growth and the dead bark. Burning should destroy all dead wood. Cover the wounds with
Root rot – The bark and wood of the roots rot and turn brown with white growth around them. The affected trees show signs of wilting, early leaf fall and heavy fruit setting before collapsing. Rotting may also lead to toppling of the tree.
To control apply Bavistin 50 % WP 10 gm along with Vitavax 75 % WP 5 gm in 100 liter water per plant along the trunk and around the drip area twice, once in April-May and again in September-October. Immediately after the treatment apply light irrigation to the plants.
CITRUS FRUIT (110 plants per acre)
Canker – The disease affects the leaves, twigs and the fruits. Canker appears as yellow spots on the leaves, which grow in size and become brownish. These spots are encircled by yellow halo. On the fruits they become rough and are confined only to the rind. Kagzi lime and grapefruit are highly susceptible to this disease.
To control an application of three sprays of 100 ppm Streptomycin, the first in October, the second in December and the third in February are recommended.
Scab – Small dark brown, rough, and irregular raised lesion mostly on the underside of the leaves but can also affect the twigs and the fruits.
To control spray
Foot rot – The trunk bark at ground level dies affecting the wood and gumming.
To control disinfect the wounds on the trunk with a disinfectant solution and then cover the same with
PLUM & PEACH FRUIT (90 plants per acre)
Shot hole – Dark brown, scattered lesions appear on the leaves that grow rapidly and finally shot holes appear on the leaves.
To control spray Captan or Ziram or Thiram 0.2 % at leaf fall or bud swelling stage.
Bacterial canker – The main trunk, branches, shoots, fruit, blossoms, dormant buds and leaves can be affected. Circular or elongated water soaked gumming lesions appear on the affected site. The bark splits, becomes brown, gummy and sour smelling. The plants above the affected site normally die.
To control apply Mashobra paste (5 kg Mashobra paste is made up of water 5.50 liter, Lanolin, 225 gm Satiric acid, 425 gm of Marpholin 150 gm, and Streptociycline) after cleaning the wound before the rains. Repeat the
process on any new affected area noticed during the following months.
Method of preparing various fungicides is given below:
Wound Disinfectant Solution
Mercuric Chloride 1 gm
Methylated sprit 250 ml
Water 750 ml
The solution can be stroed in a Glass or Procelain container. It should be applied with cotton.
Copper Sulphate 2 kg
Water 15 liter
Quick lime 3 kg
Water 15 liter
Take the lime and mix it with 3 liter of water out of the 15 liter water and then add it to the balance water. Mix to two solutions thoroughly. Apply the paste thus formed to the cut ends with a brush.
Monohydrate Copper Sulphate 1 kg
Hydrated lime dust 2 kg
Boiled linseed oil 3 kg
(Monohydrate Copper Sulphate can be
made by heating the Copper Sulphate
crystals over fire. Place the crystals
on a twa and heat till they crumble in
to white powder)
Mix the Copper Sulphate and lime dust thoroughly in the linseed oil. It can be stored for one year.
Bordeaux Mixture 2:2:250
Copper Sulphate 3 kg
Quick lime 2 kg
Water 250 liter
Dissolve 2 kg of Copper sulphate in 125 liter water in a glass container. The 2 kg lime should be dissolved in 2-3 liter water and then the balance water added to make it 125 liter. The two solutions can then be mixed and strained so that no lumps are there. The Bordeaux mixture thus prepared is alkaline. It should turn red litmus paper blue. In case the test fails add some additional quantity of lime solution till such time the red litmus paper turns blue.