Early in the second half of the last century, phylloxera was recorded from North America south of France, where it is found in the Mississippi River basin and in the eastern United States on wild grapes of the genus Euvitis. From there it spread with unusual rapidity to all wine regions. It is now almost ubiquitous in industrial winegrowing areas.
The damage caused by phylloxera
When the phylloxera pricks root tissue, it secretes saliva whose enzymes cause defects in root tissue development and deformation of the root tissue at the prick site. Flat growths, nodules called “beaks” (nodositis) appear on the thin melliferous roots, which soon die off. Thicker conductive roots develop thickened yellow outgrowths (tuberosites), on which cracks appear over time. However, remember that phylloxera itself is not the only cause of root detachment and bush death: fourereactive bacteria, saprophytic fungi that play a decisive role in the rotting and subsequent weathering of rootlets penetrate into these cracks.
The formation of nodules on the roots of grapes makes nutrient uptake difficult and may even stop it completely. Halvaks proliferate on stronger roots, isolating entire root groups and causing starvation and eventual death of the bush without meeting its nutrient needs from the soil.
The death of grape bushes after a phylloxera infestation can occur in 3-5 years in young vine plantations and much later in old ones. The timing depends on certain unfavorable other conditions in the vineyard (soil, fertilizers, climate). The duration of bush death depends on the genetic resistance of the variety. There are unstable varieties (most European varieties, Amur grape varieties, European Amur hybrids, etc.). There are tolerant (relatively resistant) varieties. Frontignac and its variations (Frontignac Gris, Frontignac Blanc) and some others (mostly European-American hybrids and hybrids of complex interspecific origin).
Only American grape varieties that we use as rootstocks and some hybrids from direct producers can be considered resistant to phylloxera (with varying degrees of resistance). Why are they considered resistant? It’s not that phylloxera doesn’t feed on their roots, it’s that despite being infested with phylloxera, their roots are resistant to the root rot process. Of the other American grape species, the American Vitits Labrusca L. grape species is considered the most resistant to phylloxera, as in hybrids produced with it (Isabella, Lydia, Concord, etc.). However, this species is still more resistant than European grapes
In primary infestation, the activity of the pest first manifests itself in weakened growth of the aerial part of the bush. Growth becomes weak, shoots ripen poorly, leaves and bunches are smaller, and the crop ripens poorly and is of poor quality. Such weak, poorly ripening shoots often die from winter frosts. Since phylloxera from an affected vine bush spreads mainly to the neighboring grape bush, a “circular foci” picture often occurs. In the progressive stage, the bunches die off faster in the center of the lesion. Next comes an area of the grapevine that already bears more or less damage and lesions. Particularly large amounts of phylloxera are found on the outskirts of the zone with apparently healthy grapes. Directly leaf phylloxera in mass infestation impairs photosynthesis, weakens vine bush growth, slows shoot maturation and leads to lower yields.
Important: The most likely sign of phylloxera infestation in grapes is a weakening of annual growth for no apparent reason.
If you notice weakened growth of grape bushes on your plot, it is necessary to check the suspicion of phylloxera, for which you need to dig up the roots. To do this, the bush is gently dug up from the side, taking into account several thin and thick roots. If you find bloats, nodules, growths, etc., as well as rotting root cavities, you need to know that it is about phylloxera, only if you find the corresponding larvae or eggs with a magnifying glass!
Why? Because such damage can come from nematodes. Read a great overview of nematodes here: Nematodes in the vineyard
And, of course, this should be reflected in the appearance of the phylloxera leaf shape. This is a “danger” signal! There is another important point. Many people confuse the leaf form of phylloxera with the manifestation of leaf lesions zudnema (grape scab) and begin to panic beforehand.
However, there are differences, and they aredramatic (See photo).
In the photo: 1 – the upper part of a grape leaf affected by the zudnemus 2 – the lower side of a grape leaf affected by the apple. Photo by Krasokhina S.I.
In the photo: 1 – top of a grape leaf infected by phylloxera 2 – bottom side of a grape leaf infected by phylloxera. Photo by Krasokhina S.I.
Life cycle and form of the pest
The life cycle of phylloxera is extremely complex. There are exclusively underground or above-ground forms, as well as those that create a connection between these forms (complete and incomplete phylloxera development cycle).
Aphid forms found only on roots and subterranean organs, all without exception are female. They are wingless, yellow-green to brownish in color, and have small, symmetrically arranged dark spots on the back. The body is broadly shaped. A long sucking liana extends from the head to the abdomen. Both the three-member tentacles and the six legs are short. With a magnifying glass, you can see three eye points on each side of the head. Just reached aphids are 0.35 mm long. After four molts, the adults are no longer than 1.35 mm in length.
The root form pierces the roots of the vine bush with its proboscis to suck out food. Due to the components of saliva, curved or elongated flat outgrowths called beaks appear at the ends of the hut roots; flat or thickened outgrowths called nodules appear on older parts of the roots.
Incredible females lay a cluster of oval yellow eggs for 4-6 weeks. The average size of the eggs is 0.32 mm, and they are half as wide. The number of eggs varies greatly. The oat aphid lays up to 800 eggs under favorable conditions, sometimes even more, but the next three generations lay fewer eggs. The number of eggs decreases to a few in poorly nourished or more susceptible (tolerant) grape varieties or in excessive numbers. With increasing age, eggs become olive to brownish-green in color. Duration of development depends on temperature and averages 8-10 days.
The root form usually produces 5-6 generations annually. Already in mid-summer, but especially in autumn, the rebel larvae slip out of the eggs with a particularly long proboscis. They feed mainly on old, less often young roots of grapes and hibernate on them to hibernate motionless and with tentacles. Hibernating larvae are resistant to low winter temperatures. As soon as it gets warmer, they stick their stings into the tips of the roots and turn into female aphids, which start laying eggs from late May to early June. Thus, we are talking about a sexless life cycle that occurs exclusively in the ground.
The winged form
Important! The natural propagation of the rebus occurs through the winged form, which leads to the leafy form and then to the root form.
In summer and early fall, thinner orange specimens appear under the root leaf louse, which are characterized by darker lateral approaches of wings above the middle pair of legs. Here we are talking about so-called nymphs. Many of them develop on some American grape varieties (rootsticks) in favorable weather and humidity.
Nymphs rise to the floor surface and turn into winged forms after the fourth (last) molt. They are about 1 mm long, yellow-green to ochreous in color, with well-developed eyes, long tentacles, and much longer legs. Equipped with two pairs of wings, they can fly short distances. Like the root form, they are always female and lay unfertilized eggs of two sizes in small numbers, especially on the loose bark of old wood and only exceptionally on the lower part of leaves near veins or on buds. However, they prefer American grape varieties and interspecific hybrids, which they perceive with a well-developed sense of smell.
Male larvae hatch from the small eggs laid by the winged form, and female larvae hatch from the larger ones, which undergo four molts to the adult stage and reach sexual maturity. The intensely yellow males are 0.28 mm long, while the light yellow females are almost 0.5 mm long. The sexually mature form has no wings or proboscis, so they cannot feed on their own. Nevertheless, they live eight days and sometimes longer. After fertilization, usually the only sexual act in the reborne life cycle, each female lays a single fertilized egg in the cracks and crevices of old, usually two- to three-year-old wood. This so-called winter egg is olive to brownish in color, 0.27 mm long and half as wide.
Late (gallic) form
The following spring, at the beginning of shoot growth, a wingless, always female aphid, called the May aphid or gall aphid, emerges from the winter egg. Previously, it was assumed that it could live only on the leaves of American varieties and hybrids of grapes, but not on European varieties. However, there is now much evidence that leaf phylloxia can also be found on European grape varieties. On European grape varieties, the pest settles with migratory larvae (vagrants) of the root form and migrates short distances from bush to bush along cracks, along roots under the ground and on the floor surface.
The photo shows the leaf form of Phylloxera in the European variety Kishmish, photo by Xokhina S.I.
The leaf form of Phylloxera is firmly established on one of the first six leaves (usually 2-5 leaves) and begins sucking on the upper part of the leaf. At this point, the leaf forms a concave green and sometimes reddish bile on the underside that surrounds the aphid and can be the size of a pea (Mai Galla). Communication with the external environment is through an opening at the top. The hairs prevent access by other insects
The photo shows the so-called Mai Galla on the leaves of aphids, photo by Xokhina S. I.
The gall aphid lays up to 1,200 yellow-green oval eggs in the galls without fertilization for several weeks. This number can be much lower for resistant grape varieties and weak to the pest nut. After 8 to 10 days, the young aphids hatch through a hole on the top of the leaf and crawl up the shoot to form on young, not fully developed leaves and a new gallery. These young aphids are called the leaf form. There are always leaves without galls between leaves with May gall and those with second-generation aphids, which develop from the May gall in the period before the aphids emerge. Second-generation leaf aphids can be on leaves 7-22. Leaves fall off, more often 9-12. Leaves on green shoots from mid-July. In addition, the third generation is formed on 18-20. Blatt gallul. Typically, the appearance of the gall is observed at the end of June and in July. Under favorable weather conditions, a fifth generation may even appear in the fourth, so that eventually all young leaves are covered with gall, although the average number of eggs laid by old aphids decreases from generation to generation. If the bush is very heavily infested, even tendrils, petioles, and shoot ends become covered and deformed (see photo).
Photo by Krasokhina S.I.
If gall-forming aphids for some reason can normally exist for American grape varieties, it sometimes happens that the leaf form of the next generations takes over neighboring European varieties growing next to infested American varieties or hybrids and forms galls.
Beginning in the second generation, increasingly larger masses of aphids, whose bodies are stronger and longer, appear in the galls along with the leaf mold, which causes new galls to form on the leaves, by fall. Such forms appear from the fourth generation. We are talking about root aphids living in the leaves, which migrate from the leaves to the soil, then to the roots of the bush, where they continue to live. Leaf aphids, on the other hand, die when the leaves fall. Therefore, they appear every year in the cycle, including the winged aphid, the sexual form, and the winter eggs. The root form is not proven to directly burst and form galls on leaves under natural conditions.
In addition to the simple cycle occurring entirely underground, where generations of the root aphid succeed one another, there is also a large, complex two-year cycle of the root form and nymphs, passing above ground through winged and germinated forms, one winter, one winter egg, a winter egg, a leaf-form, and by the time it is delayed in leafing, the root form in the soil again. That is, Phylloxera has two cycles of development and only one individual resumes the population.
Like other creatures, phylloxera also come in different breeds and biotypes, as evidenced by the unequal colonization ability of the so-called leading varieties. The earlier and then perhaps correct notion that this is a physiological differentiation is no longer supported by such external features as, for example, the length of the stabbing bristles. Whereas today one sometimes speaks of short-bowed and long-bowed phylloxera, the former is understood to be an aggressive race of phylloxera with a large grape variety.
Spread of the pest over short distances can occur due to the active movement of young root and leaf aphids and winged aphids.
Immediately after emerging from the egg, the root form is quite mobile and goes into the ground in search of new vine roots, using cracks and crevices in the ground to do so. Sometimes it may also be on the ground surface, where it can move for hours at a maximum speed of 3 cm/min without rest or food. The same applies to the shape of the leaves and roots of the winged aphid, which can travel considerable distances for its size. It has been proven that the winged form can fly up to 100 m.
Passive transmission is undoubtedly to blame for the spread of phylloxera. Specimens crawling on the surface of the ground can move with rainwater or mud flow, but particularly long distances are carried by the wind. The winged form is transmitted by wind for many kilometers, and even at distances of 30 km and probably such transmissions have caused infestations in plantations of American grape varieties, strains, and hybrids. Winged forms produce a sexual generation. Root larvae can move from bush to bush both underground and on the ground. People themselves are the main contributors to the spread of the pest. The spread of phylloxera to new grape growing areas can occur through the transfer of tools, shoes, and clothing of grape growers. The main methods of spreading phylloxera:
- planting material
Animals (e.g., rabbits, birds) also contribute to the spread of the pest.
Warning. The most important and the only reliable method of controlling reblau is the use of a refined grapevine crop.
Information on grape varieties used as a basis for vineyard protection against Reblaus can be found here: Reblaus – resistant documents The direct control of the root form of Reblaus while maintaining vines is still an unsolved problem, since due to the underground lifestyle of the aphids, the successful use of effective chemical preparations against Reblaus is extremely difficult. In the past, there have been recommendations for the use of carbon disulfide and other substances for soil treatment, but their ineffectiveness has long been proven. There are recommendations to use treatments against the leaf form of reblous by alternation of preparations of organophosphorus group and pyrethroids, but besides not very great therapeutic effect, it leads to increase of pesticide load on the vineyard and deterioration of ecology. It is believed that on weak-sandy, sandy, loamy loess soils with high content of sandy particles Reblaus lives and develops worse, which hinders its growth and exercise, which is why such soils are preferred for vineyard planning. The second extremely important condition is the quarantine of plant material. Seedling roots are thought to be the main carriers of rebush. However, the official plant protection position is that cuttings can also be distributors of reblaeus – in the form of winter eggs that are laid by females at the base of the buds. It is advisable to treat any grape planting material you receive. How to do this is the first post in the forum thread in the special topic “Reblaus. Propagation and control methods. Treating seedlings”. There you can also find many interesting discussions and debates on the subject, as well as practical experience on the subject.
When stemming the planting material, it is important to observe the doses of drugs and the time of exposure, otherwise the planting material rooting may deteriorate.
Diseases on grapes – methods of control and prevention
Vineyard damage by diseases and pests can be prevented with proper knowledge and quickly stopped. One of the most common specific vineyard problems is the occurrence of reblaus, a microscopic insect that can damage vines while they are in their underground part.
- What is a reblaus?
- root reblaus
- winged reblaus
- Sexual reblaus.
- Latt’s (gall) rebus
- Causes of lesions
- Signs of grapevine lesions
- How to combat reblaus on grapes?
- Home remedy
- Special products
- agricultural practices
- Reblaus – resistant grape varieties
What is a reblaus?
A monophagus, a species of small insect in the family Phylloxeridae, about 1 mm long, that can live and reproduce only on the grapevine. The extremely dangerous quarantine pest has an incredible survival rate. This is facilitated by its specific digestive system and unique developmental cycle that includes several stages: root, wing, floor, leaf (yolk).
Larvae can hide from the winter cold up to 3 meters deep in the floor. In spring, when the soil warms to +13 ℃, they begin to feed intensively on the juices of “sucking” grape roots. About 20 days are enough to fatten the females: underground rooters and winged settlers.
Root phylloxia is very damaging to the plant because it is impossible to recognize the pest right away. All insects are wingless yellow-green females. There are black spots symmetrically located in the upper part of the body. In order to drill a root, the pest uses a sharp drill.
Proliferation is based on the principle of parthenogenesis. 1 Female lays up to 100 eggs. Up to eight generations occur during the warm season.
Insects in the nymphal stage have thin orange discounts on the body and wings. Four stages of molting await you after reaching the surface of the earth. If you have gained full wings, place two types of eggs in the bark:
- large ones, from which the females emerge;
- small ones to produce males.
The insects flutter easily and freely between the grapes to find the best places for the eggs.
Individuals are “planted” by the eggs of the winged phylloxera. The latter go through four stages of development to sexual maturity. Males are distinguished by their dark yellow color, with a body length of about 0.28 mm. Females are lighter in color and grow to 0.5 mm. The sexually mature species lives about 8 days and does not eat anything, as it has no suitable organs: neither wings nor vines. After fertilization, the females hatch in the cracks of the thick bark.
Latt’s (gall) rebus
Female larvae hatch from leaf phylloxera from eggs laid on the stem in the spring. They are galls that deform the leaves. The process of forming a new generation of females is accompanied by improved feeding. Each phylloxera can produce up to 500 eggs. After 8-10 days, the new larvae spread through the leaves and form galls.
The phylloxera can produce nine generations in a season. Some of the larvae expand their range, and they go deeper into the ground. This is how they turn into the root phylloxera, and the cycle closes.
Causes of lesions
It is impossible to completely eliminate the possibility of grape infestation. There are a number of factors that greatly increase the risks:
- Unwanted climatic conditions for grapes (cold, rain);
- Failure to comply with the rules of agrotechnics for growing grapevines;
- Use of contaminated gardening equipment;
- Purchase by suppliers of planting material that has not been tested by an epidemiological well.
The best environment for phyllovera to develop is loose, moist substances. You will almost never encounter this aphid on sandy floors or heavy liquid loads.
- There is now a danger of new forms of phyllovers trying to survive the pest’s widespread eradication.
Phylloxera causes enormous losses in industrial viticulture. Like the Colorado potato beetle, it came from North America to the Eurasian continent. This happened back in 1860. American varieties like Vitis Riparia show high immunity against rootstock phyllox. The varieties of wine vine that have been bred by European and Asian gybes and the American Vitis Labrusca have had increased resistance to the pest.
How the phylloxera spreads:
- Floor-crawling pests carry rainwater.
- Winds carry the pest long distances;
- Phylloxera can hide in grafting, infested seedlings are very common;
- Quarantine parasites enter plantations with clothing, damp in the garden disinfecting equipment;
- Wild animals can carry the pest on themselves.
At present, the pest habitat covers the grape-growing regions in all corners of the world. In Russia, phylloxera are concentrated in the Kuban, the Crimea and the North Caucasus, where viticulture is traditionally practiced on a large scale.
Signs of grapevine lesions
The dangerous pest can be seen on the leaves of grapes. The insect often merges with the system, making it difficult to identify it.
Identify the lesion by the following sure signs:
- Reddish tubercles on the top and back of the deformed leaf (these are galls).
- If small pests can be found on the leaves, the roots of the vine are also affected.
- Yields are greatly reduced, up to the absence of mature bunches.
- The vine grows slowly after development. Young bushes die in 3-5 years, the old ones last longer.
On the root system of plant material affected by phylloxera, you can see numerous or single suspicious carpels, the roots are brittle, they can crumble.
How to combat reblaus on grapes?
Every year new rules of agrotechnics and chemicals are developed, folk methods of control are used. It is best to use all of these in combination.
The most effective referents:
- 100 g put on a tire and thoroughly dissolve in a bucket of warm water. Treat the plantation after each rain.
- Mowing the vine with a 3% solution of iron vitriol (which is thoroughly sprayed on both sides of the leaf, treat all shoots).
- Irrigation of the basal area with a 5% solution of iron sulfate. To make the liquid lick at least 20 cm, make wells first, then close them.
- Spraying with an infusion of tobacco leaves. 2 cups of leaves (fresh or dried) pour 10 water and incubate for 12 hours. After straining, the grapes are thoroughly treated.
The effectiveness of folk remedies can be observed in the early stages of the lesion. Therefore, a combination with a chemical prescription is desirable.
A special drug that has a narrowly targeted effect on phylloxera is the chlorological compound hexachlorocyclohexane in a certain concentration. In extreme cases, an aggressive treatment with this strong pesticide is carried out with mass damage to the plantation by the pest.
- Warning. Highly specialized preparations can be used only by special services, which should report a large lesion of phylloxora – wine mountain.
To destroy phylloxia, vineyard treatment is recommended three times: in spring after the appearance of the first pair of leaves, then at the end of May and in June.
Effective, proven and available insecticides are Aktellik, Midit, Iskra, Karate, Marshal, Confident. It is necessary to strictly follow the instructions for the preparations and precautions.
If there is a danger of phylloxera spread in the vineyard in the fall or early spring (during the cold off-season), it is recommended to completely flood the area with mixed chemicals. Replacing the sand when replacing the topsoil has good results, as phylloxera need moist, pliable soil to survive.
- Shrubs with lots of phylloxera are dug up and burned.
Preventive measures to prevent phylloxera infestation:
- Following all rules of grapevine care, starting with selection of planting material and site;
- Purchased planting material kept in quarantine to recognize and eradicate the pest;
- Regular thorough inspection of the plantation for early signs of infestation;
- regular pruning and destruction of damaged parts of the vine;
- keeping gardening tools perfectly clean;
- Planting vines in loose, sandy soil;
- Thoroughly uprooting diseased bushes and disinfecting the soil with chemicals.
We recommend paying attention to grape varieties that can withstand damage from the quarantine pest.
Reblaus – resistant grape varieties
Most varieties bred in the United States are resistant to phylloxera. They can be used as rootstock for zonal vines. Resistance does not translate into phylloxera not touching grapes, only that root damage is not as fatal to the vine.
The best resistant varieties are Concord, Lydia, and Isabella. Relative immunity in the following varieties: Riesling, Frontignac, Danko, Rubin, Citron Magaracha, Augustin, Bianca, Gift of Moldova.
Constant monitoring of the plantation is also necessary when choosing a variety that is resistant to grape aphids, and observing agrotechnics. Only early detection of the quarantine pest will help save the plantation with minimal losses.