Massachusetts Certified Horticulturist
Massachusetts Certified Commercial
Applicator # 35436
Insects and Diseases
A few of our top
Innovations in the production of naturally occurring beneficial microorganisms have revolutionized our ability to combat pests in a completely safe and responsible manner.
Insects such as this Black Cutworm, the larvae of a moth, often cause substantial damage to lawns that are improperly fertilized or too closely mowed. This fully grown larva is looking for a place to pupate (build a cocoon).
Proper fertilization and correct turf height reduce the stresses that can lead to disease, insect and weed infestations.
Predatory (stingless) Wasps, which help control moth and beetle larvae, are encouraged by organic gardening practices.
Gypsy Moth egg masses
can even be found on evergreens such as this Arborvitae.
females are flightless. She mates in the leaf litter in Nov. & Dec., after which she runs up deciduous trees and lays her eggs in crevices and cracks around branch unions. The eggs are then vulnerable to sprays of dormant oil, an effective organic treatment to reduce the numbers of the green inchworms that have been so damaging to our native trees.
Pictured above are the mines and larvae of the Boxwood Leaf Miner
. They overwinter at this stage and tunnel out in the early spring once they pupate. The adult is a tiny orange fly. Treatment is Neem Oil when the fly is present.
another common pest of our boxwood, Boxwood Psyllids
, a tiny insect that many small yellowish flecks, which are actually minute mines in the leaves. In large they can be quite destructive.
Close view of boxwood leaf miner eggs.
Fruiting bodies of Volutella leaf & stem blight which are typically salmon colored.
This Rhododendron was damaged by Black Vine Weevil
. The BVW feeds on the roots when immature, and then as an adult is a nocturnal pest of Rhododendron and Yew. Sometimes leaf disease enters the Weevil wound, as is the case with the above example. Aside from burlap traps which are practical on a small scale, the only organic means of them is with Predatory Nematodes
. Beneficial Nematodes, which are microscopic worms, when correctly applied to pre-moistened soil, work well.
Scale insects on a young dogwood.
These were so few in number and the tree so small that I wiped them off with a rag. The best organic treatment is often hand removal.
and vital energy away from growth. The spores by this stage infect Apple and Crabapple. The red circular lesions found on the leaves of infected Malus species produce spores which blow onto the Eastern Red Cedars causing infection and these jelly-like growths. After these run their course the branch dies. Control with copper when the rust disease of the alternate and quince are maturing in June.
Another serious disease of Cedar is Phomopsis Tip Blight
which kills the growing tips of Many juniper species well as Cypress. Kabatina Blight
is another serious disease of and Cypress.
Diplodia Tip Blight leaves the needles shortened and useless. The twigs and then the major branches die, killing the tree in only a few years. Diplodia can move through whole stands of hard pine in a short time. This disease seems to be hastened by the presence of spruce mites which open up wounds allowing fungus spores an opportunity to enter.
Diplodia is best treated with organic copper in the early Spring.
These photos of European Beech and White Birch were taken in Woods Hole. They show the effects of advanced Verticillium Wilt. Notice the scarring and the deep furrows.
Verticillium enters through the roots and advances upwards along the grain of the wood. It kills the Cambium which is the thin layer of cells between the bark and the sapwood. It is the Cambium which grows into both the bark and the wood. The brown stain on the bark is from another fungus called Bleeding Canker (phytophthora). Verticillium Wilt and Bleeding Canker are often found together and Bleeding Canker can be an early indicator of a Verticillium problem.
Verticillium attacks most deciduous trees, especially, Maple, Elm, Beech, Ash, Apple, Cherry etc; Oak is considered resistant, however, it readily attacks stressed Oaks. Verticillium is probably the most common killer of deciduous trees here on Cape Cod. It is not a quick killer since trees are able to wall it off rather effectively. The problem comes when the disease breaks through the callus wall the tree builds. It's association with Bleeding Canker probably helps in this regard.
The standard treatment for Verticillium Wilt was to inject a fungicide directly into the trunk of the tree. However, the process is costly and the chemical Fungisol
is a known carcinogen. Recently an alternative treatment has been developed. Deep root fertilization of organic fertilizer such as Neptune's Harvest Fish and Seaweed Fertilizer combined with Actinovate,
roots and prevents root diseases and that in the roots, such as Crown Canker of Dogwood. Actinovate and Neptunes Harvest has proven incredibly effective, giving failing trees a new lease on life.
Crown Canker of Dogwood
At first it looks like mechanical damage. This is especially true of young nursery stock. Don't be fooled. My experience is that most dogwoods offered for sale are diseased. Look carefully at the entire stem, from roots to crown.
Crown Canker starts in the roots and produces necrotic areas on the stem just above ground level. Flaking bark on older trees is a symptom. Brushing away the loose bark will reveal the wound (below).
As the disease progresses the top begins to decline as in the photo below.
Evidence that the above wound is caused by Crown Canker is the of dead bark still covering some of the
Below right, a new has begun to crack the inner bark and cause the outer bark to flake. Below left, half of the crown of this young dogwood has died.
, a disease of stone fruit like this Flowering Plum, can be serious if not treated early. There is no cure for Black Knot. Removing the affected branches is the only treatment.
Black Knot is most often seen growing on the native Black Cherries.
Woody Oak Gall is caused by a wasp but is sometimes confused with Black Knot. Serious infestations cause branches to weaken and the tree to put out twiggy growth. The best way to treat is to inject insecticide directly into the trunk of the tree.
Fir-Blueberry Rust is a serious problem for our Canadian Hemlocks. Hemlocks, which are related to Fir, suffer from mites which open wounds. The Rust disease enters through these wounds in the spring. The needles eventually fall, leaving the tree in distress. Treating for the Mites with dormant oil is often all that is required. However, rust is effectively controlled with parasitic bacteria such as Serenade or Actinovate which is discussed above under Wilt. Blueberry is the alternate host of this rust disease.
Weakened Hemlocks are often attacked by Hemlock Wooley Adelgid
, a serious pest of all Hemlocks. Wooley Adelgid is easily controlled by timely sprays of dormant oil.
This Arborvitae has two problems. The waxy white Juniper Scale is easy to see but another serious pest is the Spruce Mite which causes the pale speckling on every leaf scale (Juniper leaves are called scales.) Spruce mites are exceedingly tiny. They are so tiny that they are spread by like fungus or mold spores. However, the damage they do is severe and ubiquitous. Virtually every conifer suffers from spruce mites to one degree or another. When they feed they inject a toxin into the wound which weakens the tree and keeps the wound open. These open wounds are then susceptible to disease. Treating with dormant or summer oil is a fine organic way to deal with these pests. They are best treated before they lay eggs in the early spring.
Phragmites (frag-might-) or Common Reed is an attractive yet devastating exotic invasive weed. Nothing can grow alongside it for long. It chokes out all native plants that animal species need which grow on the ecotone. The ecotone is the narrow band of vegetation that grows at the edge of woods and waters or woods and prairie or any place the soil is good but there are no trees to shade out the often fragile plants which can only grow there.
The other cost of Phragmites invasion is to our views. Here in we have some of the finest views in North America. These views are not only comprised of distant overlooks across the bays and sounds but also intimate views across our ponds and marshes. These views are made special by the diversity of plant life growing together. A good example of this is along Surf Drive which has Vineyard Sound to the South and Salt Pond to the North. The view out over the sound is exquisite but the view across the Salt Pond is in some ways it's equal. The Oaks, Maples and large Cedars across the pond and the grasses and smaller trees such as Chaste Tree and Bayberry etc which grow in the ecotone in the midst of the grasses and the amazing Marsh Hibiscus. On the near side, on the ecotone by there are smaller Cedars which are shaped by the winter winds. These grow among Bayberry and Beach Rose and American Beach Grass. The random layering created by these varied plants is stunning at any time of year. However, notice the rapid invasion of the Phragmites and how this view is being systematically destroyed. It started by the parking lot at Elm Rd. and is working way westward.
Pond by pond and marsh by Phragmites is costing us our views and our native plants such as the Marsh Hibiscus. We now have safe, effective relatively means of eradicating this invasive. Second Nature has been at the forefront of the research the Conservation Commission conducted.
Organic Weed Control
which is the acid in vinegar is fairly effective in controlling weeds in beds and shrub and tree plantings.
In lawns, corn gluten can help problem areas that are too thin to prevent Crab Grass and other problem weeds. Corn gluten forms a breathable layer on top of the soil that prevents seed germination. Foot traffic can break this layer in high traffic areas so it is best to determine the underlying cause or causes of the thin turf. If it is not a fertilization or water issue, it is most often a soil structure issue.
Poison Ivy Control
is truly a wonder of the plant world. It is able to grow in full sun or dense shade. It grows as a ground cover, a vine or a shrub. It thrives from deep forests to sunny meadows, sand dunes, and right down to the high tide line of both salt and fresh water. Research has shown that the increase in carbon dioxide (CO2) has caused Poison Ivy to produce more Urushiol (oo-roo-she-all), the oil responsible for the allergic reactions. Urushiol is present in every part of the plant, leaves, stems, and roots. Contact to even a small amount of this chemical is enough to cause extreme dermatitis.
Once exposure has occurred there is a window of an hour or so when the Urushiol can be washed off. Soap is rather ineffective for this purpose. Dish detergent and shampoo work better but need several with hot water to remove it. There is a good line of products called Tecnu
. These products work and are locally available.
Generally, to remove Poison Ivy from a heavily infested site I manually cut it out and pull up the roots and haul it away. Then, when the roots that are left send up shoots, they can also be removed. There are several alternatives to this. The first is to cut the shoots off at ground level and paint the stub with Round-up. The Round-up is pulled down into the root and kills the plant. Or, visits every two weeks to remove the shoots that emerge once the vines have been cleared.
All photographs are the property of David Brogan and Second Nature.