These moths, just like the Noctuids, cause damage to cyclamen at the caterpillar stage (green caterpillars) especially on young and adult leaves.
As a rule, they are eliminated by the same chemical measures as used against Thrips; nevertheless it is a good idea to make sure that these insects do not get established, for their attacks can ruin the cyclamen for commercial purposes.
Leaf-rollers are insects in the family Tortricidae of the order Lepidoptera (butterflies and moths).
As with other moths, development is in four stages:
As in the case of the Noctuids, it is the caterpillars which harm plants, especially those grown for their flowers and ornamental plants like the cyclamen.
The Leaf-rollers get their name from the fact that, with the exception of a few species, the caterpillars spin silk and live inside rolled-up leaves.
Others have other modes of life, living in flowers or in the hollow of stalks, in bark, inside fruit, &c.
The Cabbage Leaf Roller is a common species in central and northern Europe on herbaceous plants, including various garden and glasshouse plants. Under glass it is a ubiquitous pest, which attacks ornamental plants such as roses, gerbera, alstroemeria, azalea and cyclamen.
Like the noctuids, the tortrix do not fly by day; they only move around after dusk.
Under glass this leaf-roller is found all the year round; there are 8 to 12 generations, which overlap. Outdoors, there are only two (a first generation between early June and July, a second in August and September) and an over-wintering phase for the caterpillars that hatch from the eggs laid by adults of the second generation).
Caterpillars appear from May to September; they are heavy eaters, and feed on leaves, flowers, flower buds and stalks, especially from young shoots. In some cases the corm itself may be attacked. In addition to eating from these various parts of the plant, the caterpillar spins threads which it uses to descend to the ground when disturbed. It also weaves a kind of web which it rolls itself up in, and which rolls up the leaf also. The chrysalis stage also takes place in some of this woven material, inside rolled-up leaves.
The caterpillars also foul the plant with their excreta.
Outdoors, a first generation of tortrix moth appears from early June to July, sometimes even earlier. Tortrix moths are good fliers and so can quickly infest a glasshouse; and the invasion spreads from one house to another.
Cacoecimorpha pronubana causes fearsome damage all over the Mediterranean region, and can sometimes be found on cyclamen as well as other plants.
Generally there are four generations in a year. The adults appear from April to October, with a peak in May/June and another in late August/early September. The larvae of the third generation are usually the ones that over-winter.
The caterpillars do considerable damage: destruction of terminal shoots, flower buds, young flowers... The result is a general slowing of growth and the destruction of many flowers.
They also soil the upper parts of the plant with their excreta.
Epichoristodes acerbella arrived in France in 1971. The damage done is similar to that of the Carnation Leaf-roller; indeed it is hard to distinguish the two except by the appearance of the adults.
The first adults appear from March to May; from June onwards, the generations overlap. Larval over-wintering is mostly in glasshouses, for sub-zero temperatures are lethal. Larvae also over-winter among the plant stems.
The caterpillar is most destructive of the plant.
They get through huge amounts of plant material.
Young leaves and older ones are browsed and holes are made until they are completely dried out. The threads and weavings make the leaves twist and roll up, and tie them to each other in webs of silk.
The caterpillars can also gnaw at the base of stalks, which makes the leaves on the stalks wither; and they attack flowers and flower buds also.
Another tortrix, Cnephasia (probably Cnephasia incertana, the Light Grey Tortrix Moth) has been identified on cyclamen. Though they are also great eaters of plants, there is seldom a large enough population to cause severe economic damage.
Carnation and Pear Leaf-rollers are susceptible to the poison types Bacillus Thuringiensis 3a and 3b.
There are many commercial preparations available, in the form of powders containing the resistant spores of the bacterium and the protein-like crystals.
As for the timetable for spraying, the instructions on the label should be followed; it has to be understood, though, that it is more effective against young caterpillars. Quick action then is needed to limit the damage, since caterpillars can go on feeding for some hours after ingesting the bacillus, and so the damage continues.
The effectiveness of this means of control depends on climatic conditions, and it cannot be used in all cases. For use on cyclamen, the climate in France is not damp enough.
Chemical controls can be applied to the young caterpillars. When they get older and weave their protective webs and leaf-rolls they become considerably less accessible to plant protection chemicals.
A combination of egg-killing and caterpillar-killing chemicals as well as systemics should be used from May/June to November, for full protection.
It is important to treat early (as soon as the first moth arrives) and be sure to give the heart of the plant a through coverage.
The constant development of the regulations and homologations of phytosanitary treatment products, and the differences in regulations according to each country make it impossible for us to include updated information on homologations. Each producer will have to contact his local plant protection bureau to obtain the latest updates concerning the regulations and use of phytosanitary products. We strongly advise testing beforehand on a plant sample in order to measure the chemical’s activity (establishing the dose) and any effect on the plant (plant poisoning).
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