We often do not realize thatbad neighborhood of plantswe facilitate the development of diseases and pests. These are diseases and pests that need two hosts in their life cycle. Diseases can include various rusts, such as white currant rust (affects currant bushes and five-needle pines) or pear rust (attacks pear and Sabinian junipers). Of the pests, two hosts need numerous species of aphids, such as the spruce-larch cane (it attacks larch and spruce) or the poplar-carrot cotton (as you can easily guess - it attacks poplars and carrots).
These are, of course, only examples of diseases and pests of plants that use for their developmentbad neighborhood of plantsIn order to effectively fight them, one should abandon the cultivation of pairs of plants that favor the development of a given disease or a given pest. Here are more examples onplant bad neighborhood , and details on symptoms and methods of combating diseases and pests that attack these couples.
White currant rust on the pine trunk (1) and on the underside of the currant leaf (2) and on the upper side of the currant leaf (3)
Bad plant neighborhood - rust
White currant rust
Symptoms:Yellow discoloration appears on the leaves of currants (most often black currants), turning into brown spots with time. On the underside of the leaves you can see yellow-brown or black clusters of fungus spores.In turn, on the shoots of five-needle pines (most often on the White pine, but also on the eighteen, Himalayan, small-flowered pine and limba), spindle-shaped thickenings several centimeters long.In these places, at the turn of spring and summer, smaller or larger yellow-orange, bubble-shaped spore clusters are formed. The disease is especially dangerous if it attacks the main shoot, as usually the spreading necrosis leads to the death of the entire pine.
How it becomes infected:The spores of the fungus come out of the thickenings on the pine shoots. When transmitted by the wind, they infect currants. In turn, the spores formed on the currant infect the pine needles, and then the mycelium grows into its shoots.
Methods of combating:To avoid this pine disease, first of all, do not grow five-needle pines near currants. At pine trees, cut out the affected shoots. If symptoms appear on the main shoot, the diseased area should be cut with a sharp knife as far as he althy white wood tissue, and the wound should be smeared with white emulsion paint with Score 250 EC.Spray the currant bushes before flowering, after flowering and after harvesting.You can use fungicides: Dithane NeoTec 75 WG, Polyram 75 WG, Score 250 EC, Miedzian 50 WP. The cultivation of mugwort in the vicinity of currants is also helpful, or spraying with preparations prepared from this plant.
Pear and juniper rust
Symptoms:In spring, from April to May, yellow-orange spore clusters form on juniper branches. Initially, they have the shape of cushions, then they grow to the form of cones. The bark within the enlarged thickenings cracks, and the part of the shoot above the growth turns yellow, turns brown and dies. In time, shoots with juniper rust appear completely dead. Bright red spots appear on pear leaves. In these places the leaves thicken and stiffen. Black peaks are visible on the upper side of the discoloration. In summer, yellow clusters of spores of the fungus form on the lower side of the leaves.
How the infection occurs:In spring, the spores of the Gymnosporangium sabinae fungus are released from the orange clusters visible on the juniper shoots and infect the pear leaves developing during this period.Another species of this fungus - Gymnosporangium confusum - attacks hawthorns in a similar way. The infection with Sabine junipers occurs in the fall. Pear rust is probably one of the most famous plant diseases that use in their development cyclebad neighborhood of plants
Pear rust - infested pear leaf and juniper shoot
Control methods:Avoid cultivating the Sabine junipers near pear orchards. Avoiding such company, however, does not completely solve the problem, as the fungus carried with the wind can infect pear orchards at a distance of even several kilometers.
After noticing symptoms on junipers, unfortunately they must be removed and burned. Until recently, spraying of rust-infected junipers was recommended. However, 3 years pass from the moment of infection to the appearance of symptoms. And when the symptoms are visible, the junipers cannot be saved.
In the case of pear rust on the plots, we can use Score 250 EC.Spraying is best done when the spores of the fungus released from the junipers infect the developing pear leaves. It takes place at the turn of April and May. Spraying is performed in the last decade of April, and then repeated after 10 days. If rust has occurred in recent years, it is worth spraying pear trees preventively every year.
Currant and sedge rust (also called gooseberry rust)
Symptoms:Yellow, slightly convex spots appear on the leaves of the currant and gooseberry from early spring. Yellow-orange growths develop on the underside of the leaf blade at the spots. Similar symptoms appear on herbaceous shoots, petioles, flower stalks and fruits. Infested fruits usually fall off.
How it becomes infected:The fire stage develops on currants and gooseberries. Further development stages of gooseberry rust occur on sedges. The occurrence of the disease is favored by the presence of wet meadows and wastelands in the vicinity of currant and gooseberry crops.The sedges growing in the meadows make it possible to undergo the full development cycle of rust. A long and warm autumn is a factor contributing to massive sedge infections and good development of wintering spores. After overwintering, the fungus infects gooseberries and currants.
Methods of control:If in recent years the disease was present on currants and gooseberries, and there were conditions conducive to infection of sedges and development of wintering spores, perform preventive spraying before flowering of gooseberries and currants. We can use Dithane Neo Tec 75 WG. However, the disease does not appear very often.
Bad plant neighborhood - aphids
Spruce-larch volcano
Symptoms:You can observe aphid larvae on larch from spring. They cause discoloration of young needles. When you bring the magnifying glass closer to the needles, you can see tiny yellow spots where the insect has pierced it. In summer, the shoots are covered with a sticky white fluff, under which the geotheria feed and multiply.
On the spruce trees, however, we can observe the so-called galls, that is, oval sprouts up to 12 mm long, resembling cones. Galls appear at the tops of this year's shoots. Initially, they are light green, then they turn brown. The galls ripen from the end of June to August, then they open up and the next stage of aphid development - the so-called nymphs. The nymphs transform into winged forms and fly over the larch.
Methods of combating:Avoid planting spruce trees among larch trees. In spring, before the vegetation starts, we spray Promanal 60 EC. During the growing season, the feeding forms under the sticky white coating can be destroyed by spraying with Mospilan 20 SP or Confidor 200 SL. Gauls found on spruce trees must be removed and burned (they must be removed before they mature and free themselves from nymphs). If we are not able to remove all the galls, we water the spruces with Confidor 200 SL.It will be taken by the plant from the soil and distributed along with the plant juices inside the galls.
Elm and currant cotton wool
Symptoms:Elms are the primary hosts of this aphid. Larvae hatch from the eggs hibernating in the crevices of the bark of elm trunks in spring. Under the cover of flocculent, bluish or whitish waxy secretions, they feed on the underside of the leaves, causing them to curl. Curled leaves thicken and turn yellow. In June and July, winged forms appear that fly to secondary hosts - currants and gooseberries. Aphid colonies, covered with white waxy secretion, form on the roots of the affected currants and gooseberries. They weaken the growth of shrubs. In the fall, the aphids return to the elm and lay their eggs on them.
Combating:We avoid planting elm trees near the cultivation of currants and gooseberries. In the fall, after the leaves fall or in the spring, before the buds break, spray the trunks and elm branches on which the aphids were feeding with the oil preparation Promanal 60 EC or the zoocide with contact effect Fastac 100 EC.During the growing season, spraying with Mospilan 20 SP or Confidor 200 SL is carried out.
Elm and pear cotton wool
Symptoms:As in the case of the elm and currant cotton plant, elms are the primary host (especially the 'Wredei' variety). Aphid eggs hibernate in elm bark. From mid-April, when the first leaves develop, the larvae hatch. As a result of their feeding, single, large (25 to 50 mm in diameter), baggy growths appear on elm leaves, initially green-yellow, later yellow-brown. In the second half of June, the pest flies to pear trees. It inhabits their roots, where it spends several generations and hibernates there. In September of the following year it again flies to elm trees and lays eggs in their bark.
Fighting:We avoid planting 'Wredei' elm trees in the vicinity of pear orchards. Spraying the same as in the case of the elm and currant cotton plant.
Cotton poplar and carrot
Symptoms:This aphid develops on poplars in spring.As a result of feeding the larvae, pear-shaped, reddish outgrowths are formed on the leaves of the poplar. Since June, winged individuals have been flying to the carrot beds. The pest also feeds on the carrot roots, sucking the juices out of them. Carrot growth is inhibited and the yield decreases. We can observe a powdery coating on the carrot roots. The greatest harmfulness of the cotton plant is in August and September, when the growth of the root mass is the highest. In autumn, in September or October, winged individuals appear that fly back to the poplars and lay their eggs under their bark. In the form of eggs, the pest hibernates and grows again on poplars in spring.
Fighting:Carrots should not be grown near poplar clusters (the pest can travel up to about 1 km). After noticing signs of feeding on carrots, speed up the harvest to harvest the carrots before serious damage is done to the cotton plant. Spraying is unlikely to be used in amateur crops on the plot (in commercial crops spraying with Pirimor 500 WG helps, spraying should be repeated after about 10 days).As a preventive measure, growing aphid-repellent plants - peppermint, garlic and anise - in the vicinity of carrots.
This article, of course, does not exhaust the topic of diseases and pests that usebad neighborhood of plantsAnd so, for example, among the more common pests of vegetables, we can also mention the hawthorn-carrot aphid or the poplar-lettuce cotton plant. After getting acquainted with the subject, it turns out that there are many more threats of this type that attack pairs of plants. However, it is impossible to list all of them on the pages of our guide. I hope we have listed the most important ones and this article will help many readers. I encourage you to independently search for knowledge in this field and use it in crops on the plot and avoidbad neighborhood of plants
