Learn about the pests that damage grapevine and its control.
1. Grapevine Leafhopper, Erythroneura Spp. (Hemiptera: Cicadellidae):
Wherever grapes are grown, various species of leafhoppers are almost invariably found sucking sap from the lower surface of leaves.
Life-Cycle:
The adults pass the winter in protected places, usually under plant remnants on the ground. During spring, they become active and feed to some extent on any green plant before the grape foliage appears. Eggs are laid in leaf tissues and they hatch in about 14 days. The pale wingless nymphs feed on the lower surface of the leaves and moult five times before changing into adults. The developmental period requires 3-5 weeks, depending on the temperature. There are 2-3 generations in the season.
Damage:
Both adults and nymphs suck cell-sap causing the foliage to become blotched with tiny white spots. Under heavy infestation, the leaves turn yellow or brown and fall from the vines. Since their feeding seriously interferes with normal photosynthesis of the plant, both the quantity and quality of fruits are greatly affected.
Control:
Spray 625 ml of fenitrothion 50EC or 3.75 kg of carbaryl 50WP in 1250 litres of water per ha, after rainy season when the jassid damage increases.
2. Grapevine Thrips, Rhipiphorothrips Cruentatus Hood (Thysanoptera: Heliothripidae):
This is the most destructive pest of grapevine in India and is also seen feeding on rose, jamun (Syzygium cuminii) and ak (Calotropis procera).
Both the adults and nymphs cause damage by sucking cell-sap from the leaves. The adults are minute, being 1.4 mm long, blackish brown, with yellowish wings. The nymphs are yellowish brown, just visible to the unaided eye as minute fast-moving streaks on the underside of leaves or in the centre of various flowers, particularly the rose.
Life-Cycle:
The pest breeds during most of the year, except in winter, when it is found as a pupa in the soil at a depth of 8-18 cm under the host plants. The adults appear in March and lay eggs on the undersurface of leaves by making small slits in the plant tissues, placing one egg in one slit. A female, on an average, lays 50 eggs which are dirty white, bean-shaped and can be spotted as little bright specks when affected leaf is held against a source of strong light.
The eggs hatch in 3-8 days and young nymphs appear as reddish active creatures which become yellowish brown, as they grow older. They feed on the underside of leaves by rasping the surface and sucking the oozing cell-sap. They are full-fed in 9-20 days and during the season of active breeding, they pupate on leaves.
The pupae possess power of locomotion and crawl away when disturbed. In 2-5 days, they change into adults which also feed like the nymphs. The females can reproduce with or without fertilization; the fertilized eggs hatch into females and unfertilized eggs hatch into males. The insect hibernates as a pupa in the soil from December to March and, during the active period, many generations are completed.
The parasitoid associated with this pest is Thripocentus maculatus Wat.
Damage:
Plants suffer because of constant feeding by large number of insects. The attacked leaves take a whitish hue, acquire a withered appearance, and then turn brown. The leaves ultimately curl up and drop off the plant. Such vines either do not bear fruit or the fruit drops off prematurely. Even the somewhat mature fruits are of poor quality.
Control:
(i) Remove grasses from orchard and prune infested leaves.
(ii) Rake the soil periodically.
(iii) Spray 500 ml of malathion 50EC in 500 litres of water per 100 vines, once before flowering and again after the fruit set.
3. Grapevine Leafrolier, Sylepta Lunalis Guenee (Lepidoptera: Pyralidae):
The leaf-roller is a serious pest of grapevine, especially during August-October. Its occurrence has been reported earlier from southern India and it has also assumed pest proportions in many Punjab vineyards. Besides feeding on the grapevine, this insect has also been found on eleven different species of the family Vitaceae.
Only the green caterpillars cause damage. The adults are dirty brown, with white spots on the fore and hind wings. The wing, span of the male moth is 22-24 mm, whereas that of the female is 25-28 mm. The abdomen is light brown, the terminal segment being dark brown. The full-grown caterpillars are cylindrical and measure 26 mm. The body is covered with hairs and the head is brownish-black.
Life-Cycle:
The pest is active from August to October. The moths lay creamy white oval (1.4 mm across) eggs on the lower surface of the leaves. The number of eggs laid by a female varies from 98 to 120, the pre-oviposition period being 1-3 days and the oviposition period 2-3 days. The eggs hatch in 2-3 days. The first instar larva is tiny, dirty green and measures 3-5 mm in length.
After 2 days, it changes to the second instar, which also lasts 2-3 days. The body length of the 2nd, 3rd and 4th instar larvae is 6, 11 and 18 mm, respectively. There are five larval instars and pupation takes place inside the leaf-rolls. Later on, the pupa falls to the ground on fallen leaves and debris. The pupal stage lasts 6-7 days.
Damage:
The young caterpillars (1-3 instars) feed on the lower epidermis of the leaves and skeletonize them. The grown-up larvae (4th and 5th instars) roll up the leaf margins towards the mid-rib with one caterpillar in each roll.
Control:
(i) In the initial stage of attack, remove the rolled up leaves and destroy them with larvae/pupae within.
(ii) Spray 1.25 litres of malathion 50EC in 1250 litres of water per ha as soon as the attack starts.
4. Grapevine Beetle, Sinoxylon Anale Lesne (Coleoptera: Bostrychidae):
In India, the grapevine beetle is commonly known as ‘ghun’ and is one of the most important pests of grapevine. Its distribution covers France, Italy, erstwhile USSR, Japan and China. It is primarily a pest of grapevine but also feeds on sal (Shorea robusta), teak (Ouglinia dalbergioides, Boswellia serrata), shisham (Dalbergia sissoo), wooden packing cases, etc.
The adult is sturdy, walks slowly and flies rarely. Typically, it is dark brown and measures 4.25 mm in length and 1.8 mm in breadth. The diagnostic three-bladed antennae and a pair of spines on the posterior elytral extremity are present. The full-grown larvae of the beetle are thick yellowish-white curved grubs, often found feeding along with the adults, when the infested vines are split open.
Life-Cycle:
This pest is active on dormant vines. After winter sets in, the adult beetles bore into the living woody stems and branches. Eggs are laid in galleries constructed by adult beetles inside the attacked portions. After hatching, the grubs continue feeding inside. The activity of the pest is accompanied with a peculiar crackling noise, followed by the ejection of a dusty material from the exits of the feeding-galleries. The multiplication of the pest continues in the dead vines throughout the year.
Damage:
Damage is done only to the dormant grapevine. The adult beetle constructs a circular hole, extending to the centre of the stem and then makes longitudinal galleries and forms a number of exits. The damage is always found about 30 cm above the ground level.
Both adults and grubs cause damage by feeding inside the vine-stem. All plant parts above the point of attack dry up completely. The pest prefers the late sprouting varieties, such as Anab-E-Shahi and Selection 7 and its incidence varies from 26.6 to 63.5 per cent.
Control:
(i) Clean cultivation including removal of loose bark coupled with careful pruning and destruction of infested parts will be very helpful to prevent infestation by the beetle.
(ii) Spray the vines with 1.5 litres of monocrotophos 40EC or 2.5 kg of carbaryl 50WP in 1250 litres of water per ha.
5. Grapevine Girdler, Sthenias Grisator Fabricius (Coleoptera: Cerambycidae):
The grapevine-girdler is becoming a serious pest throughout the grape growing areas in India. Beside grapes, the stem-girdler feeds on rose-bushes, mulberry, various garden shrubs, creepers, crotons, etc. The other host plants of this pest include mango, almond, jack-fruit, Bougainvillea, yellow oleander and Indian ash-tree. Girdling by the adults is followed by drying up of the wood in which the grubs can then tunnel easily.
Life-Cycle:
In spring, the adults become active at night, mate and deposit eggs in clusters of 2-4 underneath the bark of girdled branches. A slight bulge on the bark adjacent to the transverse cut indicates the location of eggs underneath. The eggs are oval, 4 mm long and 1 mm wide in the middle. Each egg is enveloped in a white parchment-like covering and hatches in 8 days. On hatching, the tiny grubs (2-4 mm in length) immediately tunnel into the wood.
Their head is dark brown and the mouth has a pair of prominent mandibles, each with two teeth. The most conspicuous part of the grub is the globular thorax, having a few chitinous spines on top. These probably aid in tunnelling into the wood. The full-grown grub is 10-12 mm long. The life-cycle is completed in more than a year. The adults appear again late in summer, but they hibernate during winter.
Damage:
During the day, adults hide on the lower side of leaves, under the forkings of branches. The girdling of green branches is an essential event before egg-laying. This results in considerable damage to the vines, as they dry up above the point of girdling.
The bark and wood are cut right up to the centre and, at times, even the branches are cut into two bits. Girdling is done at any place from 15 cm to 3 metres above the ground. Branches varying from 1.25 to 2.50 cm in thickness are preferred.
Control:
(i) Cutting and burning of attacked branches below girdling point, and hand collection and destruction of beetles may help in mitigating the beetle.
(ii) Chemical control measures are same as for grapevine beetle.
6. Flea Beetle, Scelodonta Strigicollis Moltschulsky (Coleoptera: Chrysomelidae):
This is one of the most destructive pests of grapevine in India and is found throughout the country. The adult is a shining beetle with metallic bronze colour and 6 dark spots on the elytra and is about 4.5 mm long.
Life-Cycle:
The female oviposits in the bark or in the soil and eggs may be laid singly or in groups of 20-40. A female lays 220-569 eggs during its life of 8-12 months. Eggs hatch in 4-8 days and the grubs feed on the roots and the larval period lasts 35-45 days. The full grown gmbs pupate 6-8 cm deep in the soil and emerge as adults in 7-10 days: The life-cycle is completed in about two months.
Damage:
Both the adults and the grules cause damage, the former being voracious feeder are very destructive. The adults eat up and bore into the buds, nibble the leaves making a number of holes on them, scratch the tendrils and eat the epidermis of the branches. The affected buds or sprouts soon dry up. The grubs feed on the cortex of the roots and cause considerable damage.
Control:
(i) Remove the loose bark after pruning.
(ii) Adult beetles may be collected and killed.
(iii) Spray 2.5 kg of carbaryl 50WP or 3.5 litres of chlorpyriphos 20EC in 1250 litres of water/ ha, after pulling out the loose bark.