Pierce's disease of grapevine

along the margin or the tip from early to midsummer. The necrotic area spreads over the leaf from the margin and is marked by a chlorotic band. In the beginning [...] substance, in the vessels. The bacteria, gum and tyloses block the vessels, causing the plants to wilt. Transport to different plant parts depends on the plant [...] trees. In the latter, it may stay limited to certain branches. When the leaves mature, slightly raised gummy lesions occur on the underside of the leaves

Leaf stripe

first occur on the first, second and third leaf and subsequently on other leaves. Yellow stripes are formed at the base of the leaf and the leaf sheath [...] during the cropping season. The fungus is seed-borne and this systemic infection is the only source of primary infection. The fungus spreads from the seed [...] and chlorotic and may merge. Eventually this leads to the death of the leaf. The leaf splits at the end which makes it look shredded. This is typical for

Impatiens thrips

deposited in the leaf tissue, while subsequent stages are found on the upper- and undersides of the leaf. Pupation occurs on the leaf rather than on the ground [...] ground. The prepupae and pupae remain immobile on the leaf tissue. Adults are found on both upper- and undersides of the leaves. This species of thrips is [...] piercing the cells of the surface tissues and sucking out their contents, causing the surrounding tissue to die. The resulting silver-grey patches on leaves

Leek moth

and mines the green leaves. On reaching the third instar, the larva penetrates the young leaves, the flower stalk or the inflorescence of the host plant [...] meshes spun on the surface of the leaves or on the flower-stalk of the host plant. The pupa is 7-8 mm long, its colour varies from light yellow in the beginning [...] can occur. On leeks, larvae mine the central leaves which have long, longitudinal grooves when growing. On onion leaves, the larvae feed on the parenchyma

Crazy roots, hairy roots, crown gall

galls on the stems, which are first white and later turn brown. Only Rhizobium radiobacter causes galls and tumours on underground plant parts and on the [...] crown gall The primary source of infection by Rhizobium rhizogenes has not yet been defined. The assumption is that the bacteria survive in the soil, but [...] caused by a change in the hormonal system of the plant resulting from the Rhizobium infection. Rhizobium rhizogenes puts a Ri-plasmid in the plant tissue and

Bacterial wilt, brown rot

us roots on the stem. The vascular stem tissue is coloured brown and when the stem is cut, bacterial slime oozes from the wound. This is the way to distinguish [...] signs of wilting during the day which may disappear in the early stages of infection. Under conditions favourable for the bacteria, the whole plant will wilt [...] knives and tools Control root rot nematodes as the wounds they make on roots help the bacteria to infect the crop Do not use cut potatoes for propagation

Box tree moth

at the outer margin and a characteristic white spot on the forewing, while the other is mostly light brown with a white spot on the forewings. The adult [...] Damage symptoms The larvae of the box tree moth ( Cydalima perspectalis ) feed on the leaves of box trees, but can also attack the bark of the trees, causing [...] mainly. Severe defoliation can lead to the death of the tree. As the tree is extensively traded within Europe, the box tree moth ( Cydalima perspectalis

Foot rot of cereals

humidity, the conidia germinate and penetrate the host's tissues. Inside the plant, the fungus colonizes the root and lower stem, leading to the characteristic [...] staining of the lower nodes. Long dark streaks may also appear at the stem base. On older plants, infection can produce a true foot rot, where the stem base [...] obvious bleaching of the ears. The presence of orange/pink spores may also be visible on infected spikelets. As the crop ripens, symptoms become less visible

Hemispherical scale

surface distinguish the species from most other soft scales. The size depends on the host plant and can vary from 2 to 4.5 mm. The young nymphs are white [...] form and with a raised H-pattern on the dorsal surface. All instars live on the underside of leaves, often close to the midrib. Only when an infestation [...] causing build-up of sticky deposits on nearby surfaces. The honeydew may attract attendant ants and sooty moulds grow on the sugary deposits. Badly fouled leaves

Garden chafer

feeds on roots of grasses and clover. The adults feed on the leaves of trees like oak, hazelnut and birch and on the flowers and developing fruits of, [...] cherries. Damage symptoms The garden chafer ( Phyllopertha horticola ) does most of its damage in the larval stage when it feeds on the roots. First instar larvae [...] mainly feed on small humus particles, second instar larvae on fine roots of grasses. Third instar larvae can also feed on bigger roots. After the roots have