Content
Iris diseases can be caused by viruses and fungal pathogens. To correctly recognize the problem and cure the plant, you need to study the symptoms.
Signs and causes of iris disease
Iris is a beautiful flower that enters the decorative period in early summer. Healthy perennials delight the eye with colorful buds and vibrant green foliage. But sometimes iris is attacked by fungi and harmful insects. In such cases, the following symptoms appear:
- yellowing of leaves and stem;
- decay of the aboveground and underground parts of the plant;
- faded and weak flowering;
- brown and dark spots on leaves and petals.
The symptoms of iris diseases are very similar to each other.
There are quite a few perennial diseases and pests. But they develop most often for the same reasons, namely:
- due to the presence of fungal spores or insect larvae already on the planting material;
- due to improper care, for example, against the background of severe drying out or waterlogged soil;
- due to proximity to infected plants.
Common iris diseases and control
Most often, perennials on the site wither from numerous fungi. Also, iris can be affected by viral diseases, the latter are of particular danger.
Rust
Iris often suffers from rust caused by the fungus Puccinia iridis. With the development of the disease, the leaves of the perennial are covered with yellow-brown and brown pustule spots. Rust causes the green parts of the iris to dry out and die off, sometimes involving the stems.
Rust disease affects iris at temperatures above 12 ° C
For the treatment of the disease, spraying with colloidal sulfur and Bordeaux liquid is used. Prevention of rust consists in observing crop rotation and destruction of plant debris in which fungal spores winter.
Mosaic
The Iris mosaic vims virus manifests itself in the form of a mesh pattern on the leaves, sometimes the green parts of the perennial are covered with yellow stripes. Under the influence of the disease, iris slows down its growth, begins to produce too short flower stalks, faded or unnaturally variegated buds.
In case of mosaic disease, the leaves of the iris are covered with yellow strokes.
The mosaic virus is dangerous because it cannot be treated, the perennial is simply destroyed. You need to fight the disease prophylactically - buy material only in trusted stores, disinfect the bulbs, seeds and rhizomes of iris before planting.
Wet rot (bacteriosis)
Wet root rot is caused by the bacteria Pseudomonas iridis or Erwinia aroidea. Bacteriosis leads to the fact that the underground part of the iris rots, and the rhizome is destroyed from the inside, turning into a soft white mass. Perennial leaves turn brown during the development of the disease, dry from the tips and easily fall out of the socket.
In case of bacteriosis, the affected iris must be dug out of the ground and the decayed part of the rhizome must be cut off with a sterile knife.Then you can try to plant a perennial in a new place, if the underground part has not had time to completely collapse, it is still able to recover.
The disease develops most often with waterlogging and with a lack of calcium and phosphorus. Therefore, for prevention, it is important to feed the iris in a timely manner, do not flood it and regularly loosen the soil.
With bacteriosis, iris begins to emit an unpleasant odor
Dry rot (fusarium)
The fungus Fusarium oxysporum also causes the roots to rot. The disease affects the feeding vessels, disrupts the vital processes of the perennial, as a result of which the iris turns yellow and dries. On the lower part of the rhizome, rotten areas and a gray-white bloom first appear, and then the underground part dries up entirely.
With dry rot, the iris rhizome simply crumbles
The disease develops most often against the background of an excess of nitrogen in the soil, spores wake up at temperatures from 12 ° C in spring. At the first signs of fusarium, you can spill the earth with a solution of copper sulfate. If this does not help, then the diseased iris will be eliminated.
Gray rot
The disease occurs due to the fungus Botrytis cinerea and usually develops during flowering in rainy weather. Against the background of the disease, the stems and buds of the iris turn pale, then turn brown and become covered with a light grayish bloom.
Gray rot disease affects leaves and develops in high humidity.
In the early stages of the disease, treatment is carried out with Topsin-M, Kuproskat and Oksikhom preparations; copper solutions help well against gray rot. For prevention purposes, you need to monitor the soil moisture under the iris and observe moderation when feeding with nitrogen.
Botrytis
Botrytis disease develops under the influence of the fungi Botrytis convoluta and Sclerotium rolfsii. Usually arises in conditions of high humidity, affects perennials in early spring. The roots are covered with dry rot, sometimes mold can be seen on the bases of the leaves. The growth of the iris slows down, and by summer the green parts simply die off.
Botrytis disease affects the lower parts of the iris leaves.
The fight against the disease is carried out by spraying with Bordeaux mixture and Topaz - in early spring and then twice more until the end of flowering. If the measures did not help, then the irises are dug up and destroyed, and the soil is spilled with formalin.
Heterosporia
Heterosporium disease appears due to the fungi Heterosporium iridis and Mycosphaerella macrospora. In the middle of summer, grayish-brown spots with a yellow border appear on the leaves of the iris. The perennial begins to dry out and may die completely, especially if the fungus has infected it in the midst of the growing season.
The fight against heterosporia is that all diseased leaves are removed, and the plant is sprayed with solutions of zinc and copper 3-4 times per season. To avoid illness, it is recommended to clear the flower bed of debris in time and not to overfeed the iris with phosphorus and potassium.
Heterosporiosis affects iris first on old leaves.
Ascochitosis (leaf spot)
The disease develops under the influence of fungi from the genus Ascochyta, brown areas appear on the leaves of the iris - first at the edges, and then closer to the center of the plates. Perennial greens dry up and fall off, and if you dig it out of the ground, then dark spots can be seen on the rhizome.
At the first symptoms of the disease, Bordeaux liquid has a good effect - spraying is carried out three times at intervals of 2 weeks.
With ascochitis, iris leaves begin to darken from the edges.
Ascochitosis most often develops on iris in conditions of high humidity and waterlogged soil.
Alternaria
A fungus of the genus Alternaria infects iris from mid-spring to late summer. Against the background of the disease, the edges of the leaf plates begin to dry out, then all the green parts become covered with black bloom, turn yellow profusely and crumble.
Black spots on the iris are characteristic of Alternaria
For the prevention of Alternaria, Bordeaux liquid is used, spraying is carried out before and after flowering.If the iris is already affected by the disease, then it is better to dig it up and burn it, since the spores quickly spread to other plants.
Iris pests and control measures
In addition to viruses and fungi, pests are a great danger to perennials. Some of them are easy to spot on the leaves, others infect the root system and can quickly destroy the iris.
Onion mite
A small rounded insect with a yellowish body does not exceed 1 mm in size and feeds on iris bulbs. It is active in early spring, and in summer it begins to multiply and can give new colonies every 20 days.
The iris onion mite remains unnoticed for a long time, so it is better to fight it prophylactically.
When infected with a tick, the scales of iris bulbs dry out and shrivel, the perennial stops growing. A weakened plant is often attacked by secondary fungal diseases. The fight against the pest is carried out with the systemic insecticides Actellik and Skor, but it is better to soak the material in an Anti-mite solution before planting or sprinkle it with plenty of chalk.
Thrips
A small insect a little more than 1.5 mm in length settles on iris leaves, more precisely, in rosettes at their very base. Thrips feed on perennial juices, as a result of which it turns brown, dries up and deforms. Infected iris does not always die, but it blooms poorly or does not produce buds at all.
To get rid of the insect, you need to spray the plant with a solution of Karbofos twice with an interval of a week. From folk remedies, tobacco infusion helps well.
In hot dry weather, thrips give up to 9 new generations per season
Onion nematode
The pest is a small white worm up to 1.5 mm long and reproduces in iris bulbs in moist soil. Under the influence of the nematode, the perennial begins to grow poorly, its stems swell, and the underground part cracks and becomes loose. A distinct unpleasant odor begins to emanate from it.
It is very difficult to cure an onion nematode on an iris - the pest has time to destroy the tuber
Fighting the nematode is difficult, it is extremely hardy and usually does not respond to treatment. Therefore, the affected irises are destroyed and focused on prevention - they disinfect the bulbs before planting, monitor the moisture content of the soil and loosen the flower bed from time to time.
Bean aphid
The insect looks like a small black-green or brown beetle, lives on the green parts of the iris. The pest has been active since mid-spring, under its influence the perennial shoots are deformed, and the leaf plates turn pale and curl. If you do not fight aphids, then in the fall it will lay eggs at the roots, and in the spring the iris attacks a new generation of insects.
You can get rid of aphids with the help of Iskra, Karate and Commander preparations, spraying is carried out 3-4 times per season. For prevention, you need to pay attention to weeding and loosening, as well as feed the iris with potassium and phosphorus.
In hot weather, the bean aphid can give up to 10 generations over the summer.
Iris fly
A black-gray fly with golden spots on its body feeds on iris buds in late spring, and then lays eggs, from which voracious larvae emerge. The pest causes severe damage to flowering and plant health. Fly control is carried out with Aktara and Actellik preparations three times per season.
The iris fly and its larvae can completely destroy the iris during the summer.
Folk remedies help from the iris fly - tobacco dust, soap solution, ash.
Wireworms
Black or striped beetles lay larvae in an iris flower bed. The hatched pests feed on rhizomes and gnaw out long passages in them; against the background of mechanical damage, fungal infections often develop. The affected perennial blooms worse and grows slower, and dies with a serious infection.
The wire beetle gnaws at the rhizomes of the iris
The fight against the wireworm is carried out with insecticides Decis and Aktara, as well as a decoction of red bitter pepper.
Bronze beetle
Large greenish beetles with a metallic sheen are active from late May to autumn. In the garden, they can even be useful, as they participate in pollination. However, beetles feed on the roots and buds of plants, so they are dangerous for iris. You can notice their presence by the eaten flowers.
Bronzovik, useful in general, is harmful to iris, since it feeds on their leaves and flowers.
Get rid of the bronze beetle with the help of the Kinmix preparation, you need to spray the flower bed with irises several times over the summer. A preventive effect is brought by a solution of wood ash.
Medvedki
Large garden pest is an insect up to 5 cm long with movable jaws and strong front pincers. Medvedka lives in the soil and digs deep passages in it, damaging the rhizomes and bulbs of the iris.
Medvedka is difficult to destroy with insecticides, usually it is only driven to the surface of the earth and collected by hand
It is not easy to fight the pest, therefore, even at the stage of planting, insecticides are poured into the holes for perennials. If the beetle does appear on the site, then you can shed the soil with infusion of chicken droppings or treat the iris abundantly with Karbofos.
Scoops
At the beginning of spring, dangerous caterpillars of the iris or winter moth often appear on flower beds with irises. Pests eat the stalks of perennials at the very base, as a result of which the peduncles weaken, die off or break under the gusts of wind. Also, caterpillars can eat rhizomes and bulbs, this will harm the iris in itself and provoke the development of fungal diseases.
The caterpillars of the scoop gnaw the stems of the iris, which is why they simply break
You can get rid of the scoop by spraying with Karbofos. It is best to carry out them prophylactically, at the very beginning of spring and again in a week.
Prevention measures
Not all iris diseases are treatable, so it is easier to prevent their development. When caring for a flower bed, you must:
- control the level of humidity - flowers cannot be poured;
- apply fertilizers moderately, with an excess of nitrogen, phosphorus or calcium, the neutrality of the soil is disturbed, fungi begin to multiply more actively in it;
- regularly loosen the soil and remove weeds;
- remove faded shoots in time;
- carry out preventive treatment of iris in the spring against diseases and pests;
- disinfect planting material at the preparation stage - soaking in potassium permanganate or fungicidal agents significantly increases the endurance of plants.
Autumn treatment of iris for diseases should be carried out after pruning.
In the fall, a flower bed with irises must be carefully dug up so that fungal spores and pests cannot survive the winter in the upper soil layer. Vegetable debris from the site is completely removed and burned, before the onset of cold weather, another treatment with fungicides is carried out.
Conclusion
Iris diseases appear most often when the rules of care are violated. As part of the treatment, it is important not only to treat perennials, but also to eliminate risk factors - to adjust the frequency of watering and the composition of the soil.
