Pests Of Daylilies
Several daylily growers, display garden owners as well as breeders have now realized that practicing good agronomy is ultimately helpful for the health of their daylilies. They have also found that avoiding the use of pesticides on daylilies helps to ensure that their plants are better off in the long run. It is important to note that using excessive chemicals on the plants never helps them to develop their natural resistance to diseases and pests. At the same time, chemicals also put off the natural predators. Nevertheless, when a plant is severely infested with pests or suffering from diseases, it becomes necessary to use remedies for the plant’s good health.
All the pests that have been discussed in this article have been seen in daylily gardens at some point of time. However, it needs to be mentioned that they are unlikely to cause considerable problems every time. If you find one or two of these pests in your garden, you should not become panicky and immediately rush for control measures. It is advisable that you first assess the damage caused to your plants by these pests and see if they are able to resist or tolerate them. You will find that controls are not necessary in some cases and the problem may possibly be restricted to some extent. In some cases, even natural predators in your garden may take care of the problem, without any kind of intervention by you. However, you need to ensure that the suspect is the only one that is responsible for the damage manifested on the plants. For this, you need to scrutinize the injury carefully. Pests can harm your plants in various different ways. While some pests will chew plant parts, there are others that penetrate the plant tissues and suck out the juice. Therefore, understanding the character of the feeding damage may go a long way in identifying the actual culprit.
Always remember that you can keep your plants robust and in good health by providing them with sufficient water and nutrients. In the long run, these measures will greatly contribute in helping the plants avoid or even prevail over the problems caused by pests. It is important to note that presence of elevated amounts of nitrogen in the soil often makes the plants more alluring to specific pests.
Even if you find that your daylily plants have actually been damaged by pests, before applying chemical pesticides, you should first think of using other options. There are times when even spraying plain water from a powerful hose can be effective in diminishing the infestation of specific pests. If you are left with no options, but go for chemical pesticides, you should preferably try controls that are less toxic. In case use of such low toxin chemical pesticides does not yield the desired results – control the pests satisfactorily, and the damage is considerable, you can use other more potent chemical pesticides. However, before you use them, it is advisable that you seek local guidance regarding the selection of such pesticides. This is important because the products available in different regions usually vary. Similarly, the timing of applying the pesticides also differs from one region to another. You need to bear in mind that inappropriate use of chemical pesticides may, in fact, increase the pest problems, as such pesticides often eliminate the favourable insects. At the same time, remember that improper use of chemical pesticides can also harm your daylily plants.
Aphids (Myzus hemerocallis)
Generally, aphids survive on developing buds, thereby resulting in a wart-like appearance. The growth of plants infested by aphids retards their growth, while the foliage turns yellowish. Plants infested by this pest look as if they are suffering from a deficit of nitrogen.
Bulb mite (Rhizoglyphus spp.)
Bulb mites are minute insects that are only visible when seen under a powerful microscope. Usually, the size of these pests varies from just 0.3 mm to 0.5 mm in length. These insects survive by feeding on fungi formed on damaged roots or bulb. As of now, no chemical pesticide to control bulb mites has been developed. However, it has been seen that usually healthy plants are not vulnerable to this insect. Even if they are attacked, healthy plants do not generally succumb to bulb mites.
There are several diverse species of cutworms across the globe. These insects generally feed during the night and are usually seen while working on the soil around plants. During the day, cutworms remain curled up just beneath the surface of the soil. Basically, cutworms are caterpillars. They are the larvae of moths that are active during the night and lengthwise measure anywhere between one inch and two inches. Some cutworms gnaw the base of plants very near the surface of soil, usually resulting in the plant toppling over. There are other cutworms that climb up the plants and feed on their leaves and other parts. Subject to the species of this pest, there may be one or even more generations in a year.
If you suspect that cutworms have invaded your daylilies, it is advisable that you closely examine the area where the damage has been caused. Also inspect the top inch of the soil close to the plant and you can find the pest. Once you have discovered the culprit, remove them immediately. You may also use biological controls like Bacillus thuringiensis (BT). It is said that this biological control is most effective in dealing with cutworms when it is combined with bait composed of molasses and moist barn. Alternatively, you may also use the helpful nematodes. You can also make “collars” for small plants using a variety of things and place them around the plants’ bases. Ensure that these “collars” are partially pushed into the soil, leaving no space for the pests to creep inside the protective ring. You can also make the “collars” using substances like crushed egg shells, wood ashes, or even diatomaceous earth and sprinkle them around your daylily plants.
These nocturnal insects eat up the base of a flower’s anther and style, thereby making the flower worthless for hybridizing. In addition, earwigs also consume vast areas of the epidermis, which ruins a flower’s appearance. You can get rid of these insects by pulling them out of the affected flowers using fine tweezers. It has been noticed that earwigs have a tendency to assemble in large families. Hence, if the infestation of earwigs is severe, you can also use some chemical deterrents.
Belonging to the insect order Orthoptera, the size of majority of grasshoppers is anything between one inch and two inches and they may be green, yellow or brown in color. Grasshoppers harm the plants by eating up the leaves and stems. These insects are a greater problem in places receiving 10 inches to 30 inches of annual rainfall. Usually, grasshoppers lay their eggs in the soil during the later part of summer or early fall. Therefore, if you cultivate the ground during this period, it will automatically help to diminish their population. In fact, you can also protect your daylilies by mulching, as this will promote natural predators that will help in eliminating this insect. Alternatively, you may also cover the rows of seedlings and others with floating row covers. Nevertheless, generally, it is very difficult to control these pests. They appear in large populations and, hence, possess the ability to cause significant damage to your plants.
Hemerocallis gall midge (Contarinia quinquenotata)
Hemerocallis gall midge is a tiny white insect that lays its eggs in the newly developed daylily buds and its growing larvae feeds inside the growing flower bud. The damage caused by this insect is mainly visible in daylilies that bloom during the day time in early mid-summer. The affected buds become distorted and discoloured. These buds develop the shape of tulips and generally begin to decay even before producing the flower. If these affected buds are opened one can see minute small whitish insects, especially when placed under a microscope or seen through a hand-held magnifying glass.
If you see or suspect that your daylilies have been invaded by this midge, it is advisable that you immediately shift the affected daylily plants to quarantine area. You need to keep them in that area for the entire season and treat the basal areas of the plants with Chlorophos. This chemical will eliminate all the insects as well as the emerging pupae. If there are any scapes with distorted flower buds you need to cut them off at the base and burn them immediately to stop the insects from spreading to healthy plants. Chances of infestations by hemerocallis gall midge is maximum in places receiving too much rain either during the end of spring or beginning of summer.
Hemerocallis thrips (Frankliniella hemerocallis)
Hemerocallis thrips are the most widespread among the five thrips species found infesting daylilies. When the infestation of hemerocallis thrips on daylilies is most severe, these insects may result in shrivelling and even death of immature flowers. It has been found that daylilies with paler hues are common victims of these thrips. Orius insidious, which belongs to the stinkbug family, is considered to be a very effective biological control for this type of thrips. After devouring the thrips, Orius insidious will take on mites as well as other insects. Hemerocallis thrips have the ability to over winter in some climatic conditions. They usually take refuge in the fan of the plant where the crown is joined by the inner leaves.
Slugs and snails
These pests are common in gardens where the soil is damp or soggy. They generally assault the leaves, instead of the flowers. They take shelter in the foliage of the evergreens during the winter and harm the new soft shoots when they come out in the beginning of spring. These pests assemble at the center of mature daylily clamps and are usually discovered only when one digs up the clumps for division. However, you may check their population by practicing careful and hygienic gardening. Alternatively, gardeners and breeders may also use natural predators and chemical deterrents to control these pests.
Tetranychus urticae or two-spotted spider mites are present everywhere where you find any vegetation. These pests suck out the chlorophyll from the foliage of the daylilies making them turn pale brown and perhaps even cause the plants to die. Spider mite is a greater problem when the day is hot and the plants are not watered enough. These mites are hardly visible to the naked eyes and at times found to be covering the surface of daylily leaves forming a fine web over them. If your daylily has been affected by spider mites, it may be essential to treat them with an effective miticide.
Tarnished plant bug (Lygus rugulipennis)
Adult oval-shaped Lygus rugulipennis (tarnished plant bug) moves very rapidly and its color vary from dappled pale green to coppery brown. Usually, the adult bugs grow 5 mm (1/4 inch) in length. The fore wings of these bugs have yellow triangles with black tips and they emerge from the side of their body, slanting downward to the back segment of the wings. On the other hand, though the nymphs have five black dots on their yellow-green body and have resemblance to the adults, they do not have wings.
Both adult and nymph bugs penetrate the leaves as well as the flowering buds of daylilies and suck out their juice. In fact, compared to the adult bugs, the nymphs cause more harm to the plants. The saliva of these bugs is toxic and makes the leaves and shoots distorted. They also cause the pods and buds to drop from the plants. Some daylily plants affected by this bug will start wilting or their growth will be stunted, while the branch tops turn black and eventually die back. Whenever available, damsel bugs and minute pirate bugs are natural predators for tarnished plant bugs. If the infestation is severe, you may also spray the plants using Sabadilla or Rotenone. In addition, you can also spray a blend of oil and soap when the bugs are in their nymph stage and unable to fly. This blend will be effective in eliminating the nymphs.
Many daylily growers often complain about the damages caused to their plants by thrips, but these pests are rarely seen, as their size is extremely small and they also cleverly conceal themselves in the flowers and between the leaves. Apart from being undetectable, all thrips are not harmful. There are several thrips that are beneficial to gardeners, as they prey on various other pests. While a number of thrips survive on fungi, there are others that feed on plants, but are helpful at times since they also devour spider mite eggs, while they are still immature. Frankliniella hemerocallis is among the many different types of thrips that are found on daylilies. Usually, thrips have different colors, including orange, yellow, black or dark brown. When young, thrips usually have a whitish or yellow color. However, young thrips bear a close resemblance to the adults, except that they may not have wings like the adults.
Usually, thrips measure below 1/8 of an inch long and may be even smaller. These pests can have several generations every year. Thrips usually invade the daylily leaves and flower buds. Daylily leaves affected by thrips become discoloured – usually developing pale colored streaking or patches. When the leaves are infested by this pest, you can often see dark hued thrip droppings in the region around the leaves. When thrips invade daylily flower buds, they are distorted, develop streaks and eventually it causes bud drop. Even the daylily scapes affected by thrips can develop cork-like lesions that may be many inches long.
It has been found that usually daylily cultivars are more vulnerable to damage by thrips. Problems caused by thrip invasion are likely to increase when the weather is dry and also when the daylily plants have been fed with excessive fertilizers containing elevated amounts of nitrogen. Hence, it is advised that you water your plants sufficiently and also promote the development and growth of favourable insects, as they will be helpful in controlling the thrip population in your garden. Spraying the plants with insecticidal soap may help to reduce the number of this pest to some extent, but it may not reach the thrips that have concealed themselves deep inside the buds or among the leaves.