2023-06-07 11:03:02
Bulletin on plant protection of the BBAH until May 31
WHEAT AND BARLEY
Aphids /seed Aphididae/
Aphids
Climatic conditions are favorable for the mass multiplication and harmful activity of aphids. In some areas, density above the FIR is observed. In the regions: Veliko Tarnovo, Dobrich, Pernik, Pleven and Silistra, a density of 10-15% attacked plants was established. As a result of the harmful activity of aphids already in autumn, in the areas: Veliko Tarnovo and Dobrich, crops with viral diseases are observed with up to 30% of diseased plants.
Harmful wheat bug /Eurygaster integriceps/
The spring migration of adults from their wintering grounds to the wheat fields continues. It is established in all areas. The density is from 0-2 pcs/ sq.m. There are currently no treated areas against the enemy. Upon settling in the crops, the bugs feed by sucking sap from the lower part of the stems and causing yellowing and twisting of the central leaf. Later, they move along the upper parts of the plants, pierce the vagina and suck juice from the ear. The part above the damage site turns white. This damage is called “partial white hair”. Immediately after the cereal crops are sorted, bedbugs suck sap from the stem above the last knee. The spike is white and erect, and the last sheath is green. This damage is called “total whiteness”.
Chemical control against the adult is carried out when the ratio between the sexes is evened out, before the enemy lays eggs and when the density is above the threshold of economic harm: – 2 pcs/sq.m. m in a dry and warm spring, weak and rare crops; – 4 pcs/sq. m at normal seeding density; – 1 pc./sq. m. for seed crops;
Common wheat leech /Oulema melanopa/
Cold and rainy weather is not favorable for the development of the pest. A mass emergence of the adult has been established in almost all areas. Beginning of egg laying and beginning of hatching have been established in the districts: Pazardzhik, Pernik, Stara Zagora, Targovishte and Yambol. The density of the enemy at this point is of no economic importance from 1-10 pcs. / sq.m.
Chemical treatment against the enemy is carried out when a density above the PIV is established with the approved insecticides. PIV in the “spinning” phenophase for adults is: – 30 pcs. /sq. m – rare crops and dry spring; – 50 pcs. /sq. m – dense crops and cool spring;
Gray corn borer /Tanymecus dilaticollis/
An increase in the density of the enemy was found in the Pleven region, on individual wheat crops. The adults that attack the young plants are harmful: they gnaw through the sprouts and stems below the soil surface, and they make peripheral bites on the leaves.
Barley yellow dwarf virus
It is observed in the regions of Dobrich, VelikoTarnovo and Vratsa. The attack is on harvesters between 8-30%. Yellow dwarfing of barley has very characteristic manifestations in the spring, and diseased plants are easily recognized by them. The symptoms vary within certain limits (according to the variety), but three of them are always present: dwarfing, severe browning and intense yellow or red coloring of the leaves. The growth of diseased plants is greatly suppressed. They are retarded in development and look stunted. The brothers are numerous, compact with upright yellow to golden yellow leaves.
Wounded leafy prigor /Septoria tritici/
The pathogen was found in about 30% of the surveyed fields in the Dobrich region. Gray-green spots with a yellow crown can be seen on the leaves, which in the center are pale brown, speckled with small black dots /pycnidia/. In severe infestations, the spots coalesce and the leaves or entire plants die. The attacked plants are weak, the spikes are small, with a shriveled grain.
Brown and yellow leaf rust /Puccinia recondita/ and /Puccinia striiformis/
First manifestations of brown and yellow leaf rust were detected. The spores of the pathogen are mainly located on the lower floors of the plants. The degree of attack is 5-13 % of the attacked leaf surface. The disease is observed in 5% of the examined fields in the Dobrich region, to a higher degree mainly in the seaside AER.
In the case of brown rust, brown to rusty brown, unevenly scattered small sori are formed on the leaves, mainly on the upper side. Yellow rust appears mainly on the leaf petals, but under particularly favorable conditions it can be found on all green parts of the plants – stems, chaff, thistles and even on unripe grains, lemon-yellow elongated summer sori are formed.
Reticular spots on barley /Drechslera teres/
Spots on the lower leaves of barley were found in the regions: Veliko Tarnovo, Razgrad and Stara Zagora. Density varies from 2-7%. Infested plants do not set or remain sterile and if seeds are formed they are stunted and poorly developed.
Brashnesta mana /Erysiphe graminis/
The appearance of single pustules on the lower parts of the stems and leaves was noted in early and dense crops. In the Veliko Tarnovo region, an attack of the wheat and barley disease was detected on the middle layers of the leaves. In part of the examined crops in the regions of Veliko Tarnovo, Montana, Sofia city, Targovishte and Yambol, the attack is above the PIV – 10%-15% of the attacked leaf mass. The disease is detected initially on the lower leaves, then the signs appear on the upper ones, leaf sheaths, stems and spikes. On the surface of the affected organs, gray whitish, floury plaques form. The greatest lesions are observed when the flag leaves and spike are affected.
CANLAPE
Rapichen flower beetle / Meligethes aeneus /
The main damage is caused by the adults, which gnaw through the flower buds to feed on the pollen and lay their eggs inside. Corroded buds do not produce quality flowers. With a greater degree of attack, the entire inflorescence may dry up. With less damage, the buds form pods, but they are deformed, curved and do not grow. When rape is attacked in the budding phenophase, the damage is great. Once flowering has started, the flower eater feeds on pollen and the damage done is negligible.
Ceutorhynchus napi/
Harmful activity of the adult was reported. Single specimens are observed in Montana region. In the Silistra region, the density is 0-3 pcs. adults/sq. m., where a fight was reported. A mass occurrence was found in the Vratsa region with a density of 4-5 pcs. adults/sq. m., which is around and above PIV. The beetles feed on the young leaves, flower rosettes and flower buds of the crop. The hatched larvae bite into the stem. Attacked stems become twisted and broken.
The woodpecker /Ceutorhynchus obstrictus/
In the Veliko Tarnovo region, the reported rate of attack is 3-4 units. adults/sq. m., and in Targovishte from 0-2 units/sq.m. m. Octopuses feed on the flower buds. Females lay 1 egg in a pod. Attacked pods are difficult to distinguish from healthy ones. An external symptom on the plant occurs when the larvae leave the plant. Small openings appear on the attacked pods. The direct damage caused by adults and larvae when feeding them is not so great, but they create a suitable environment for the cabbage midge to lay its eggs on the pods.
Dry stem rot /phomosis/ /Leptosphaeria maculans
An attack was found on the lower leaf layers. In the Sliven region, 6-12% of spots on the leaves were found, and in the Targovishte region, 5-10%. A signal to perform a treatment has been submitted. The disease manifests itself from plant emergence to the 6th leaf. Irregular, rounded, gray-green spots form on the lowermost leaves, but the most characteristic signs are on the root neck, which necrotizes and cracks, and on the stems, which develops a brown, withered strip.
SUNFLOWER AND CORN
Gray corn borer /Tanymecus dilaticollis/
In the month of April, the appearance and start of harmful activity by the gray corn borer was detected in the corn fields in the regions: Veliko Tarnovo, Vidin, Vratsa, Montana, Lovech and Pleven. In the regions: Vratsa (AER Oryahovo and Byala Slatina) and Veliko Tarnovo (AER Svishtov) in emerging corn crops, a mass harmful activity and a density of 2-3 pieces/sq.m. In the Montana region, the density is 2-10 units/sq.m., which is above the PIV. The entire area was treated there. In the Pleven district, the density is above the PIV – 6-12 units/sq.m. m. In the sprouting sunflower crops, the density of the enemy is as follows: Veliko Tarnovo region – 2 pcs./sq.m. m, the regions: Vidin and Pleven – 1 pc./sq.m. m, Vratsa region – 2-3 units/sq.m. m, Lovech region – 1-1.5 units/sq.m. m and Montana region – 2-10 units/sq.m. m. Chemical control against the enemy is carried out by vegetative spraying with insecticides at the beginning of crop emergence, which usually coincides with the mass appearance of the proboscis. PIV at sunflower: – 2 adults/sq.m. m. in the “sprouting” phenophase; – 5-6 adults/sq.m. m. in phenophase “4-5th leaf”; PIV for corn: – more than 2 pcs. adults/sq. m. in phenophase until “5th – 7th leaf” or 20-30% damaged leaf mass;
Field cricket /Gryllus campestris/
Density of 2 units/sq.m. in corn crops was observed in Veliko Tarnovo region (AER Pavlikeni). The attacked area of 0.016 thousand ha has been treated. Harmful activity of crickets has also been registered in Lovech district. The reported density of the enemy in the sunflower crops in the Veliko Tarnovo region is – 2 pcs./sq.m. m, Vratsa region – 1-2 units/sq.m. m, Lovech region – 0-0.5 units/sq.m. m and Plovdiv region – 3 units/sq.m. m. 0.550 thousand ha were attacked. They gnaw the young plants at the base, gnaw the buds and tender tops. Wireworms /sem. Elateridae/ In the Plovdiv region, 0.800 thousand ha of sunflower and 0.900 thousand ha of corn with rich humus soils were attacked.
Common sandpiper /Opatrum sabulosum/
Harmful activity in sprouting sunflower crops is observed in the Vratsa region on an area of 0.080 thousand ha, at a density of 1-2 pieces/sq.m. They are strongly attracted to the emerging sunflower, feeding on its cotyledons. However, the damage is greatest when the beetles gnaw through the top of the vegetation.
Meadow butterfly
Meadow butterfly /Loxostege sticticalis/
During surveys carried out in the period 28.04-02.05.2023 on the territory of the Pazardzhik region, the beginning of the flight of butterflies of the first generation on weedy areas was found. If an attack by the enemy is detected above the registered economic damage thresholds (EIA), treatment against the caterpillars is necessary. In order to prevent mass multiplication of the meadow butterfly, as well as to take timely control measures, in the event of an established attack, it is necessary that the enemy be under increased surveillance this year.
POTATOES
Wireworms /family Elateridae/
Insecticides were imported against the enemy when planting potatoes on 0.540 thousand ha. Wireworms are one of the most common omnivorous enemies and are characterized by a wide ecological and nutritional plasticity, which accounts for their wide geographical distribution. The damage is caused by the larvae. They lead an underground lifestyle, which makes it difficult to control them. Chemical control against the enemy is undertaken on areas with an established density higher than the PIV: – 4-6 pcs. larvae/sq.m.
Colorado beetle /Leptinotarsa decemlineata/
The first established damages from the enemy’s adults were registered in the Blagoevgrad region. The start of the emergence of the Colorado beetle from its winter shelters has also been detected in the districts of Vidin, Pazardzhik and Plovdiv. Chemical control against adults is carried out at PIV: – 10% populated nests when sprouting up to 10-15 cm height of the plants; – 5 pcs. adults per 100 plants at 15-25 cm plant height; -10 pcs. egg clusters on 10 plants at 15-25 cm plant height; PIV for the larvae is: – 150 pcs. larvae per 100 plants at 15-25 cm plant height;
Potato moth /Phthorimaea operculella/
The beginning of flight of the potato moth was detected in the pheromone traps laid in Kyustendil and Pazardzhik regions. Heavily attacked leaves gradually wither and die. The caterpillars leave such leaves and enter the stem, where they carve downward courses. Stems above the site of damage wither and dry.
Potato blight /Phytophthora infestans/
The first preventive treatment against the pathogen was carried out in Blagoevgrad district. At its initial manifestation, irregular to rounded brown spots with a lighter halo are observed on the lower leaves, and in wet weather, a gray-white spore-forming coating appears on the underside. Leaves begin to burn when severe spotting occurs. The infection moves to the stems, which turn brown to black brown.
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