After finally getting the vegetable and herb gardens planted and mulched and all the container plants in their proper homes, it’s time to turn my attention to the flower and ornamental beds. Annuals were added to some garden beds as I do so appreciate their cheery, season long color.

herb garden 6-20

Herb garden all weeded, planted and mulched. Photo by dmp, 2020

In the cellar door bed, 3 ‘Sunfinity’ sunflowers were planted. These are new, dwarf hybrids reaching only 3 to 4 feet tall and producing several stems, each with multiple flowers reputedly over the whole summer. We shall see. No deadheading required was on the label but I find that they look much better with the spent blossoms removed as the flowers are several inches across and the ones gone by are pretty noticeable. Their only downside so far is that they are pollenless but to make up for that I have them surrounded by sweet alyssum, a pollinator favorite, and have several rows of pollen bearing sunflowers started from seed in the vegetable garden.

sunfinity

Sunfinity, dwarf sunflower. Photo by dmp, 2020

Salmon colored salvias in one of the front beds harmonize nicely with the orange, blue and white blossoms in the window boxes above it. All was well for the first few days after setting out the transplants and then holes began to appear in the leaves. The culprit – slugs! Since it has been so dry, one wouldn’t think there would be much of a problem with them but all of the newly planted beds have been receiving copious amounts of water so the new plants could become established.

slug damage on salvia

Slug damage on salvia. Photo by dmp, 2020

The reason slug damage was suspected was two-fold. The holes on the leaves were irregularly shaped, typical of slug damage plus a slight slime trail was noticed in the morning. These soft-bodied, shell-less mollusks tend to feed at night and rest in a shaded, moist site during sunny days. One reason they always seem so plentiful is that they are not picky about what they eat. Meals may consist of your more tender plants as well as fungi, lichens, worms, animal droppings, insects and carrion. Often, they consume many times their own weight on a daily basis. Imagine our grocery bills if we needed to eat that much?

slug

Slug. Photo by dmp, 2020

Slugs produce slime to help them move and for moisture control among other reasons. To tell if your plants are being feasted on by these voracious critters, look for dried slime trails on leaves or on the ground around affected plants in the morning. Since I typically find slugs mostly in beds that are presently being regularly watered, I just use some diatomaceous earth on the mulch around plant groups and try not to get water on the DE as that lessens its effectiveness. As plants become established and watering is less often, slugs are not a serious problem for me except during rainy summers.

Next on to the holly hedge. Probably close to 25 years ago, I planted a 20-foot hedge of ‘Blue Prince’ and ‘Blue Princess’ hollies. It has grown mightily and even with regular pruning it is about 6-foot high and wide and a handsome barrier between ours and the neighbor’s house. There were many distractions last year and I really did not start noticing something was wrong with the hedge until a large bare patch appeared over the winter.

scale damage to holly

Scale damage to holly. Photo by dmp, 2020

Finally having a bit of time to investigate further, it appears sadly that my plants are infected with cottony camellia scale. These insects feed on a number of deciduous and evergreen trees and shrubs. As adults, scale insects are immobile but the females lay egg masses and after hatching, the young scales, known as crawlers, move to other locations on the plant and then proceed to cover themselves with their protective armor. This makes them challenging to control as adults. Crawlers typically hatch in June but are small and not easily seen. I used a hose end sprayer to apply a horticultural oil this past weekend and will probably do this several more times over the summer. With scale, persistence is key.

scale on holly

Cottony camellia scale on holly. Photo by dmp, 2020

While I love roses, I only have a handful growing in my gardens now including some old fashioned, own-root roses, a rambler, 2 miniatures and 2 hybrid teas. My favorite hybrid tea is ‘Peace’ as not only is it a gorgeous pale yellow flushed with pink rose with quite the history, but it also was my grandmother’s favorite and it was time spent with her that gave me my love of gardening.

Peace

‘Peace’ rose. Photo by dmp, 2019.

Leaves on several of the roses were skeletonized and checking underneath the leaves was lurking the rose sawfly larvae, more commonly called rose slugs because they secrete a slimy substance over their bodies that makes them somewhat resemble small slugs. The larvae of rose sawflies are about ½ to ¾ inch long and yellowish-green in color.

rose slug 2

Rose slug on underside of leaves. Photo by dmp,2020

The rose sawfly emerge from soil after overwintering as larvae in early spring. They mate and eggs are laid on the undersides of leaves. After hatching, the larvae feed for a month or so and then drop to the ground to pupate. Luckily the species that is attacking my roses only has one generation per year. Since I only have a few plants, I just inspect the undersides of the leaves and crush the larvae with my fingers. If large populations were noticed, I could enlist the help of some insecticidal soap or neem oil.

rose slug damage on Peace

Rose slug damage on ‘Peace’ rose. Photo by dmp,2020

I’m sure there will be many more insects to battle this gardening season, but I’ll start with these.

 

May your gardens be relatively pest free.

 

Dawn P.

Those Pesky Sawflies!

 

Those Pesky Sawflies!

Sawflies are members of the insect order, Hymenoptera, that includes ants, wasps, and bees. Sawfly adults are wasp- like and have a sawlike tube which is used to incise holes in plant tissue for depositing eggs. Unfortunately for gardeners, sawflies often lay large numbers of eggs on a single plant, and the caterpillar-like larvae can devour large amounts of plant material in short order. Sawflies are usually plant specific, so pine sawflies may have many pines as a host plant, and rose sawflies will attack many kinds of roses, but neither will find hibiscus suitable for food.

There are several sawfly species that will shortly be trouble in the landscape. Be vigilant and try to detect them as soon as possible. If you have hibiscus, mugo pine, or roses, you may have already, or will soon see damage from feeding larvae.

Rose Sawfly

This spring the rose sawfly was a problem on many roses, including the insect- resistan Knock- Out ™ varieties. The initial feeding damage from the smallest larval  instar was sometimes mistaken for disease, as leaves turned brown over time and then dried up. The larva chew the leaves on one surface, so the other side looked good until the damage was severe enough to cause browning of tissue. Most damage is now at an end, but larva may be sprayed directly with insecticidal soap  if needed. Next year, look at the leaf undersides  periodically to detect larvae as soon as possible.

sawfly Wisc.ent.edu .

Rose sawfly larvae. Photo entomology.wisc.edu

 

Hibiscus Sawfly

These sawflies are currently beginning to feed on members of the Mallow Family. Larvae are green and have dark heads, and begin feeding on the undersides of leaves, moving to the upper sides as they become larger. To catch quickly, check the undersides of leaves. They will consume every part of the leaf except the veins, and the  damage may be confused with that of scarab beetles. Manage these pests by handpicking larvae, or removing leaves having many of them. Cocoons are found on the base of the plants and can be removed and disposed of. Insecticidal soaps or spinosad are effective means of control also.

hibiscus sawfly Leanne Pundt

Hibiscus sawflies and damage. Leanne Pundt photo.

 

Pine Sawflies

There are two species of sawfly that are serious pests of pines in New England, the redheaded pine sawfly and the European pine sawfly. The European pine sawfly commonly attacks Mugo  pines in the landscape, but will also feed on Japanese, Scotch, and other pines. Usually, pine sawflies are found on  young trees that are between 1- 14 feet tall. Needle damage first appears as browning of the needles and gradually the branches will become stripped of needles. This is because the larvae feed together in large groups. If all the needles have been consumed from one tree, the sawflies will move to another nearby pine. Best control is when larvae are small to keep damage minimal.

Eggs can be removed if found on needles over the winter. Destroy the material, do not simply discard on the ground. Also, clip off branches that have multitudes of larvae, or try to knock them off into a bucket of soapy water. Summer oils and insecticidal soap can be applied to larvae feeding on ornamental pines. Make sure coverage includes all the larvae.

sawflies on white pine

Sawflies on white pine Photo copyright Pamm Cooper 2013

sawfly damage on mugo pine Illinois extension

Sawfly damage to Mugo pine University of Illinois Extension photo

Sawfly adults are hard to spot sometimes, as they appear to be wasps hanging about the garden. But aquaint yourself with the life cycles of the sawflies that are pests in your gardens or landscapes, and check for larva before you see damage. The smaller you find them, the easier it is to get rid of them.

Pamm Cooper