Korean firis a very original and decorative tree, and at the same time completely frost-resistant. Come beautiful and seemingly easy to grow, it happens thatfir turns yellow and loses needles , losing its charm. Why is this happening? How to prevent fir yellowing and losing needles? Learn about the 3 most commonKorean fir diseasesand learn how to fight them.
Korean fir diseases. Why does the fir turn yellow and lose needles?
Fig. Mikado, forum.PoradnikOgrodniczy.pl
Korean firis one of the most beautiful conifers in our gardens. In cultivation, however, it requires positions sheltered from winds and fertile and sufficiently moist soil. During long periods of droughtfir turns yellow and loses needles
Improperly selected cultivation position, weakening of the plant by frosts, damage to shoots and high air humidity may in turn become directcauses of Korean fir diseases .
Common fir spread
One of the most dangerousdiseases that attack Korean fir is common fir rashWe recognize the symptoms of rash in July, when black conidial clusters of the fungus form on the upper side of the needles. After some time, symptoms will also appear on the underside of the needles, along the main nerve, where the convex cups of the mushroom sac stage are characteristic.
The following year, in May, the sacral spores infect the plant, andover time the fir turns yellow and loses its needlesAfter observing the symptoms, do not allow the plant needles to be watered and wetted, the fir should be sprayed 2-3 times in intervals every 14 days, using alternating agents: Topsin M 500 SC and Amistar 250 SC.
Fir shoot dieback
Another Korean fir disease , which causes the fir to turn yellow and lose needles, isfir shoot diebackSymptoms appear on various parts of the plant's shoots, where there are brown spots covering their entire circumference. The part of the shoot above the spots dies. Needles growing over the site of infection turn yellow and fall off. In rainy weather, spores are transferred to neighboring plants and infect them most often at the site of damage to the shoot.Sick Korean fir shootsshould be cut below the infection site and sprayed with Topsin M 500 SC or Rovral Aquaflo 500 SC.
Phytophthora on Korean fir
Phytophthorosis is a very dangerous disease, the spores of which cause rot of the base of shoots and roots.Korean fir needles become dull, lose their shine, turn yellow with time , turn grayish and fall off one by one. On heavily infested specimens, the needles change color to red.
ThisKorean fir diseasesignificantly affects the root system of the plant. After taking the fir out of the substrate, you can see that the hair roots are strongly reduced, which prevents the plant from properly picking up water and nutrients from the soil. The rot moves from the base of the shoot upwards. What is worse, pathogens remain in the soil for a long time, so it is advisable not to plant more plants in the place of the infected plant, without at least proper soil disinfection, e.g. with Magnicur Energy 840 SL, which can also be sprayed on the infected plant.
MSc Eng. Joanna Białowąs
