PESTS and GARDEN INSECTS

 

First, a warning about pesticides. Their use can start many arguments among gardeners because of their danger to the environment. And a warning against one pesticide, in particular. Never use Kelthane! Although effective on other crops, reports I deem reliable say it can ruin your daylilies' foliage. Maybe not, but I'm not willing to try.

Some growers believe pesticides should be avoided at all costs. They report that, in the absence of pesticides, natural insect predators will increase and control problem bugs. They advocate a willingness to live with a certain level of damage.

At the other extreme are those who practice preventive 'medicine' and apply heavy pesticides as a precautionary step, with the theory that an ounce of prevention is worth a pound of cure.

I used to lie somewhere in the middle but have become convinced that pesticides should be used rarely - only in emergencies and only temporarily. Pesticides are dangerous, not only to the environment, but to your own health. (Some of the pesticides mentioned herein are extremely dangerous.)

Besides the health risk, the main problem with pesticides is that they will not work in the long run. It's that simple. They will kill good insects leaving no natural protection from the bad. Bad insects will build up tolerance. You cannot get 100% coverage of a pesticide on your plants, so the remaining bad insects will multiply quickly. Even if you could get 100% coverage, eggs of some species will hatch in 3-5 days. Pesticides are a dead end, for you not pests.

Many "bad" insects are becoming resistant to even the best poisons, while "good" ones are not. Thus you'll always kill off the good ones first, and may be left with the bad ones, anyway.

Unless you develop an immediate widespread, plant-threatening epidemic of a damaging insect, use no pesticides.

The wave of the future is biological control or Integrated Pest Management (IPM). Nature has already provided you with some biological controls for your garden. If you do not destroy it, it may be all you need. Some bad insects and some minor damage can be expected and tolerated, but sometimes an epidemic occurs. In these cases, nature needs some help.

Although in its infancy, IPM holds much promise and has made good progress already. There will be parasitic and pathogen products, in addition to the more familiar predator ones. Pathogens include viruses, bacterium, and fungi. Bacteria is already being successfully used against certain caterpillars (these do not attack daylilies), and several fungi are in the developmental stage. A product first arriving on the scene in 1996 is a fungus called 'Naturalis-O' which kills most of the daylily's small pest enemies: aphids, mites, and thrips.

The advantages to IPM include: no pest tolerance, it is target specific (it would not harm as many good bugs), it attacks pests in all stages of their lives (including eggs), it's nonpoisonous, and it has no residue.

Some natural controls available for purchase produce limited results. Ladybugs will not stay in my yard, but fly away. The same goes with praying mantis, and these will eat other beneficial insects. I suspect the same with lacewings but do not know because they are too small to see. Diatomaceous Earth (sometimes called 'DE') can help control slugs and aphids but should be reapplied after every rain or watering. For me, this is not practical, but on a smaller scale, it is worth a try.

You can even buy spider mite predators, which I now use religiously. In fact, more and more predator insects are now available and the prices fall each year as more people use them. Some predators cannot survive cold winters and thus must be replaced each year, if the problem persists.

There are also some newer, much safer pesticides that can be used: Neem or BioNeem (from Safer) and SunSpray oil (or other, new soluble oil products). Neem is a pesticide (insect control) that comes from a "Neem" tree in India. It is very safe, non-photo toxic, and gentle on plants. SunSpray oil is simply a highly-refined oil. It is not a pesticide but acts by smothering insects. Up to now, such oils could not be used on plants, because they would smother the plant leafs ability to "breathe" as well. However, the refinement process now yields molecules so small that they do not interfere with the plant host. See below for specific insect applications.

A final safety note about the use of pesticides. Although they vary in potential danger, I would suggest treating them all with extreme caution. Many require the use of respiratory protection such as a respirator with an organic vapor chemical cartridge and dust/mist filter. These are not that difficult or expensive to find, but your local Frank's nursery, Walgreen's, or Kmart would not have them. Wear long sleeve shirts and pants. Wear rubber gloves. I keep a box of disposable latex gloves on hand and wear them when using any pesticide, fungicide, or herbicide. Although I don't always do so, protective goggles should also be worn to prevent chemical splashes into the eyes. So what if you look like you are exploring a foreign planet in your protective gear; that is better than getting sick.

Anyway, here is a list of the most small pests which threaten daylilies. (For deer and buffalo, you are on your own.)

APHIDS -

Aphids are small, soft-bodied insects and are most commonly light green, brown, gray, and black. Thousands of species of aphids exist and, consequently, vary considerably in color, size, response to environmental conditions, and host preference. They are typically found clustered on the undersides of leaves and on stems. The most common group of aphids lays eggs in protected places on their preferred hosts near the growing season's end, which overwinter and hatch as females in the spring. From then until near the end of the growing season, only females are present, giving live birth to more females, which already have partially formed females within them. At the end of the growing season males are produced and females are then born with eggs rather than live young inside, which are fertilized by the males during mating. Excess sap, called honeydew, is secreted as they feed and is sweet and sticky. Other insects, such as ants and honeybees, feed on the honeydew. Some ant species guard aphid colonies, killing natural aphid predators.

If present, you can see a large group of bright green bugs in between young leaves. Dead skins, which appear as white specks, can also be visible. Aphids suck sap from soft leaf and stem tissue, causing the leaves to curl. Damage is usually warty bumps on buds or distorted leaves and fans.

Try a predator call Orius (the 'Minute Pirate Bug'). Or, I have found that they can easily be controlled with a mild pesticide, like Safer's Insecticidal soap. Neem (or BioNeem) also works.

SLUGS -

Are commonly found in the St. Louis area and can be difficult. One adult can deposit up to 400 eggs a year. Slugs can be found year-round. They are not insects but are mollusks and can be described as snails without the shell.

Slugs love wet weather and early mornings when dew is heavy. They hide under ground cover such as decaying plant material, stones, bricks, boards, feeding primarily at night. Therefore, any mulch provides a breeding ground and a refuge for them. A clean flower bed, free of mulch and debris can eliminate any serious threat.

Slugs eat the new foliage from the center of the fan, and they can consume it faster than the plant can grow it. Damage is often obvious: it looks like scalloped bite marks on the edges of the leaves. During the day, slugs hide in the soil around the base of the plant, so you do not often actually see the slugs on the plants. They do their damage at night and early morning, which is the best time to see them still slithering around.

There are many 'homemade' treatments, many of which work. Although, if you have a large collection of daylilies (or hostas, etc.), most of these simpler methods are not practical.

Note that hand picking slugs without gloves might be dangerous. Many species serve as intermediate hosts for the rat lungworm, Angiostrongylus cantonensis. Humans can also be infected by the larvae of the rat lungworm, by deliberate ingestion of the uncooked slug and also by accidental ingestion of its slimy mucus secretion.

Slug Bait, BUG-GETA, etc. can provide adequate relief, but try to find a brand containing both metaldehyde and Sevin. Metaldehyde will only stun the slugs so that the sun can finish them off the next day. In cooler weather, many will survive the day and recover. With Sevin, a pesticide, this would not happen. If you have small children or pets, baits present an obvious hazard.

Also "effective" (though not yet tried by me) is liquid DEADLINE, a snail killer.

The most effective treatment may be GRANDSLAM, but this is the most toxic chemical I have ever used and should be used with extreme caution. I no longer use it.

SPIDER MITES -

First of all, do not be needlessly alarmed. Spider mites are not usually a daylily problem for the average garden. However, by the time a spider mite problem becomes obvious to someone not looking for it, the infestation is widespread and the damage can be major. Therefore, it's worthwhile to occasionally spot check a few daylilies, by inspecting the leaf underside. Mites are very small, about the size of a pinpoint - not a pinhead. There is more than one variety, but it is the two-spotted mite that normally attacks daylilies. This is different from the red spider mite that often infests houseplants. If you see many little dots, about the size of a period in this document, stare at them for at least five seconds or so to see if they move. If the dots start to move, you may have mites. Note that besides the fact that they are small, they are also light-colored, and together it makes them hard to see. You might try using a magnifying glass or your teenage son with sharp eyesight.

The devastation occurs on the underside of the leaves, and you can see the leaves turn pale yellow, looks dirty, and then turns pale brown when the leaf is too far gone. The mites by this time have drawn the chlorophyll from the leaf. The plant loses its strength as it loses the chlorophyll. Fine webbing is possible, but I never have seen it on this kind of mite; these are different from the type of mites that produce webbing on house plants.

Once you have had an infestation, you should vigilantly inspect the underside of random plants throughout your garden. They are very hard to see, especially for older eyes. If the underside of the leaf is green, there probably is no problem. If there is any color loss, look carefully for any small spots that could be an insect. You would not see any form to it, just a dot. Many times they stand still. Stare at the dot for at least five seconds. If it is a mite, and if it is alive, it will finally move.

Mites are most difficult to get rid of, once out of control. They like hot, dry weather, but I have found them as early as late May, during wet weather. They hide on underside of leaves. For heavy infestations, reapply every ten days; it may also be helpful to use more than one pesticide and alternate them.

The best solution to bad mites is predator mites. Phytoseiulus persimilus (or simply PERSIMILUS) is the predator of choice. I use Buena Biosystems at (805) 525-2525. Natural Solutions from the Necessary Trading Company (703-864-5103) is (or was) another source. Both these people have been uncommonly helpful and accommodating. The trick is to have them (the predator mites) arrive before the bad mites get out-of-hand, but late enough so they have the heat and humidity to survive. The predators also need a food source or they will die.

As a safe and cheap alternative to pesticides or predators, mites might be controlled with simple water. Because this would be so much safer than chemicals, try it first, especially if you have no more than a small collection of daylilies. The method is to wash the mites away. Mites are extremely small and consequently crawl very slowly, perhaps only ten inches a day. Therefore, if you can knock them off with a forceful spray of water, and repeat the application every three days, for three or four times, you can get rid of them (at least for awhile). This approach is probably best for the average daylily grower, unless your garden is large.

You should always choose predator mites over pesticides, but if you must use chemicals, here are some effective pesticides for mite control:

SunSpray (oil) - not a pesticide; works by smothering mites and their eggs.

TALSTAR (miticide)

PLICTRAN (acaricide) - probably no longer available.

AVID (miticide) - possibly the best, but probably cannot be obtained in convenient, small, affordable size - unless you share with others. I have received a report, however, that says smaller quantities can be obtained through some African Violet supply houses, such as AV by Fredericks, in North Carolina. Their phone number is 1-800-771-0899 and their website is www.african-violets.com.

PENTAC (miticide) - probably the second best and most used among commercial greenhouses. It has a long residual action and will not only kill the adult mites, but will also destroy the young mites and most of the eggs for a prolonged length of time. It is available in more affordable quantities.

Stirrup-M (pheromone) - not a pesticide, but a sex attractant to be used in conjunction with a pesticide. The theory is that mites move around more and become more exposed to pesticide.

THRIPS -

Thrips eat on and damage the blooms and tender branches, not the foliage. A thrips ('thrips' is both singular and plural) is a gray-black insect about the size and shape of the upper part of a small exclamation point! Thrips are insects that are barely visible, about 5 mm or less long, and cluster along veins on the undersides of leaves. Their fecal spots and plant damage are usually more apparent than the thrips themselves. Adults have two pairs of wings that are fringed and normally held over and parallel to the body. Active feeding occurs during the adult and larval stages.

Once the bloom is open, thrips do little or no damage. The damage is done in the bud form just as the outer petals begin to loosen. The thrips rubs the bud until it 'bleeds' and then eats this liquid. Bleeding can cause the petals to stick together, and the flower is unable to open properly or not at all. This also can result in white or brown scars and distorted leaves.

If infestation is heavy, entire leaves become brownish or silver and look dried rather than wilted, similar to damage from windburn. Some species produce large amounts of black, soot-like specks of fecal matter on the leaves.

The Orius Insidiosus predator is most effective ('Minute Pirate Bug'), but thrips can probably be controlled with Safer's Insecticidal soap. Orthene will probably also work. Orius a member of the stink bug family. It will overwinter from Florida to Canada. When the thrips are gone, the Orius (or pirate bug) will then begin to devour mites and other insects.

BULB MITES -

This is the most recent pest added to this list, and the author has no knowledge or experience with them, that I'm aware of. In fact, it is unclear to me that bulb mites are responsible at all for any daylily damage. I have heard that their presence may simply be coincidental with a sick plant and get blamed for being in the wrong place at the wrong time.

If bulb mites prove to be a threat, they are difficult to diagnose because they are small and occur below ground. If you experience sporadic occurrences of "crown rot" (where the daylily truly dies), you might in fact have bulb mites instead.

As the theory goes, the mites (Rhizoglyphus exhinopus) attack first at the bottom of the crown. Without digging and inspecting this area, there is no way to otherwise tell if a plant is infested until it abruptly dies.

Because they are in the ground, bulb mites may unfortunately not be a good candidate for natural predators. In fact the best alternative to combating them may be a very dangerous pesticide that is hard to obtain: Vydate. It contains oxamyl, a highly water-soluble pesticide of the carbamate class. (Probably similar to the product GRANDSLAM, that I used to use on slugs.) Because contact pesticides are not a choice for obvious reasons, Vydate-and perhaps Cygon" -may work because they are systemic.

Hopefully we'll learn more about this in the coming years.

OTHER PESTS -

There are some other non-insect pests that can damage daylilies.

Rabbits can develop a taste for the youngest, tender daylilies. I had this problem one year, when there was a bumper crop of rabbits. Instead of killing them, I choose to use a Have-a-Hart trap, which allowed me to trap and relocate them.

I find that squirrels are a terrible nuisance, especially in winter. They continually dig around freshly planted daylilies. I suppose they simply like to bury or look for previously-buried acorns in the loose soil -it's easy digging- but they tend to expose the roots to the elements. This is another good reason to brick new plants.

Having a dog or cat in the yard will, of course, help discourage wild animals.

I have no deer near me, so I have neglected to gather any intelligence for you on how to avoid damage from them, which can be as severe (and quicker) than any insect. At least you'll see the damage, however.

MOLES and VOLES -

(much credit for vole information to Bill Watson)

I have both in my yard. While moles make your yard look ugly, they do little if any direct damage to your plants. Voles on the other hand will eat plant roots. Although I am aware of no incidence of voles eating daylilies roots in my yard, they have destroyed other plants including hosta.

Forget trying to attack moles from the runs in the middle of your lawn. Those are usually feeding runs which the mole generally goes down only once. (Why go back if the food is gone?) Instead, you need to try to find their highways, which are usually deeper in the ground and under the cover of a hedge or shrub. I have tried many remedies. Most have proven worthless for me. I have had a little luck killing a few with traps after being lucky enough to find a highway. I have had the most luck recently by poisoning them, with poisoned corn such as a product called Revenge and with a totally different poison called Rozol, but not with the traditional bait found most commonly at the local nursery.

If you have a vole problem, you have one of the greatest problem any gardener can have, especially if you grow hostas. You can see mole tunnels. You cannot see vole tunnels. They create an underground maze of tunnels. You will find exit holes about the size of a quarter where they are present. Contrary to popular belief, voles do not use mole runs; field mice do. Voles create their own runs. Voles are very small, ugly, almost tailless. They may look a little like black mice. Left alone in the garden they can create a maze so complex that the ground can eventually cave in.

There is a product called Rozol that is available at chemical supply places, not at garden centers. It is blue pellets that you pour into vole holes and cover with brick or board. If you can find it, Rozol is by far the best solution I have yet to find for moles and voles.

 

aphids
Aphids (but not on a daylily)

 

thrips
Thrips

picture of thrip damage
Thrip damage

 

picture of a slug
Slug

 

picture of spider mites
Spider Mite damage
(leaves start to look pale yellow or ivory)