Yellowing Yews (Taxus spp.) can be caused by a variety of things such as the soil being too wet or too dry, disease, insect pests, winter desiccation, salt damage, snow damage, animal grazing, animal urine, transplant shock, nutritional deficiency or too high or too low of a soil pH. Properly diagnosing the problem takes a little detective work. To complicate things, it is also quite … Continue reading Yellowing Yews
Tar spot is a common fungal disease of maple trees. The fungus attacks maple leaves in the spring causing pale spots that continue to grow in size, turning yellow then eventually to raised black spots by fall. The black spots look like spots of tar on the leaves, and thus its name. There are several species of tar spot that affect maples, with the 3 … Continue reading Tar Spot on Maple Leaves
Rudbeckia are known for being real work horses in the mid-summer to mid-fall garden. They are also known for being low maintenance and fairly pest and disease free. However, there are a few leaf spot diseases that can greatly mar the appearance of Rudbeckia, especially certain species, varieties or cultivars. Following are the leaf spot diseases to watch for on your Rudbeckia plants. Septoria Leaf … Continue reading Leaf Spot Diseases of Rudbeckia
The word fasciation comes from the Latin word fascia, to fuse, and that is often what this growth abnormality looks like. Affected stems, fruit or flowers appear as though 2 or more have been fused or banded together. At times the unusual new growth looks quite spectacular and unique, and breeders attempt to reproduce the effect. At other times affected plant material appears grotesque and … Continue reading Fasciation Causes Unusual Growth of Flowers, Stems, or Fruit
Two common diseases in both vegetable gardens and ornamental gardens are powdery mildew and downy mildew. While the two diseases have many similarities the pathogen is different, symptoms are expressed differently, and each flourish in different types of environmental conditions. Learning to prevent and recognize the symptoms of each disease is key to managing these destructive diseases. Powdery Mildew Powdery mildew is a fungal disease … Continue reading Powdery Mildew Verses Downy Mildew
Iris borers (Macronoctua onusta), are a species of cutworms that bore through iris leaves down into the rhizomes, causing browning and wilting. Their feeding damage can also cause a disease known as bacterial soft rot, aka. root rot. This bacterial disease, caused by the bacteria Erwinia carotovora, causes the rhizome to rot and become mushy, emitting a foul odour. Iris rhizomes infected with this disease … Continue reading Iris Borers and Bacterial Soft Rot
What is dormant oil? Dormant oil is an oil based, low-impact insecticide, that is sprayed on vulnerable woody plants during their dormant season, to kill the overwintering stage of pest insects. The oil used is typically a highly refined mineral oil to which an emulsifying agent has been added, which allows the oil to mix with water. Sometimes cottonseed oil or soybean oil are used … Continue reading Dormant Oil for the Control of Over-wintering Insect Pests
There are several potential causes of leaf spots on Iris including fungal infection, bacterial infection, various viruses, insect damage and various environmental factors. Of these factors fungal leaf spot is the most common and widely spread. Leaf spot diseases greatly mare the appearance of Iris plants and can kill whole leaves and eventually plants if not brought under control. Fungal Leaf Spot of Iris Iris … Continue reading Leaf Spot Diseases of Iris
In order to understand the difference between root nodules, that are caused by nitrogen fixing bacteria and root-knot disease, caused by nematodes, one must first have a clear understanding of what each is. Root Nodules Caused by Nitrogen Fixing Bacteria Nitrogen-fixing bacteria are able to transform atmospheric nitrogen (a form the plants cannot absorb) into fixed nitrogen (a form plants can absorb). There are 2 main kinds … Continue reading Root Nodules Caused by Nitrogen Fixing Bacteria Verses Root-Knot Nematode Disease
What is Lilac Witches’ Broom? Lilac witches’ broom is a serious systemic disease of lilacs for which there is no cure. Infected lilacs typically gradually decline until they die. The characteristic symptom is the development of witches’ broom (tight clusters of short, thin branches that all stem from the same point). These witches’ brooms tend to form near the base of the lilac but they … Continue reading Lilac Witches’ Broom
Clematis vines are a popular choice for ornamental home gardens. Large flowered, early blooming varieties are particularly popular. These show stopping, head turning vines both amaze and delight all who cross paths with them. A fairly common disease of clematis to be on the look out for is clematis wilt (Phoma clematidina). You will sometimes hear it referred to as clematis leaf and stem spot. … Continue reading Clematis Wilt
What is Coral Spot Nectria Canker? Coral Spot Nectria Canker is a fungal disease caused by the fungus Nectria cinnabarina. These opportunistic fungi typically attack trees and shrubs that have been weakened by stress or injuries like mechanical injury, storm damage, insect feeding, animal damage, pruning, disease, frost cracks, cold injury or drought damage. Once the fungi gain entry to the plant they cause the … Continue reading Japanese Maple Problems…Coral Spot Nectria Canker
Red twig dogwood species consisting of Cornus sericea, Cornus alba and Cornus sanguinea are prone to several fungal diseases and their coresponding fungi including powdery mildew (Erysiphe pulchra), dogwood anthracnose (Discula destructiva), leaf spot (Cercospora cornicola and Septoria) and Botryosphaeria canker (Botryosphaeria dothidea). Of these fungal diseases, Botryosphaeria canker and dogwood anthracnose are both capable of producing cankers on the stems of dogwood. To tell … Continue reading Botryosphaeria Canker of Red Twig Dogwood
Galls are abnormal growths that can appear on roots, stems, trunks or leaves. There are many woody plants that get galls and there are several different gall makers (causes for the gall formation); insects, mites, bacteria, fungi, or nematodes. The galls formed are unique to the gall maker and the genus or species it feeds on. For crown gall the disease is caused by a … Continue reading Crown Gall on Euonymus
Daylilies (Hemerocallis sp.) are popular garden plants grown abundantly by home gardeners, cities and commercial properties alike. Their appeal in part is due to their long bloom time, adaptability to a wide range of growing conditions and their relative ease of maintenance. There are a few foliar problems to be aware of, and while they seldom kill the plant, they can certainly mar the visual … Continue reading Daylily Problems
Juniper trees and shrubs are a popular choice in the ornamental home garden. These slow growing plants require little maintenance, are fairly drought tolerant, take full sun and are able to grow in a variety of soil types. They are fairly salt tolerant and make good roadside plantings. In addition to this they are evergreens and provide year-round beauty and interest to the landscape. With … Continue reading Juniper Blight
Written by Kimberley Pacholko Updated on Sept. 25, 2021 Juniper Rust (Gymnosporangium juniperi-virginianae) better known as Cedar Apple Rust, s a fungal Disease requiring 2 years and 2 host plants to complete its life cycle. In the first group of host trees you have Apple, Quince and Hawthorne. In the second group you have Eastern Red Cedars and many varieties of Junipers. The disease can … Continue reading Juniper Rust (aka) Cedar Apple Rust
Fire Blight caused by Erwinia amylovora, is a serious bacterial disease that affects many members of the rose family (Rosaceae), such as purple sand cherry, apple, crabapple, quince, pear, plum, mountain ash and more. The trees and shrubs that have been infected have the appearance of having been scorched by fire. The disease is systemic and spreads rapidly leading to extensive damage, even death. There is … Continue reading Fire Blight in the Ornamental Home Garden
Black Knot Disease otherwise known as Dibotryon morbosum, is a serious, yet fairly common fungal disease of plums and cherry trees (including choke cherries). Other members of the Prunus family (like peaches, nectarines, apricots and almonds) can also be affected but it is less common. The affected trees develop hard, black elongated swellings, called knots, thus the name black knot. These knots are scattered throughout … Continue reading Black Knot Disease of Plum and Cherry Trees
Eastern Filbert Blight is a disease caused by the fungus – Anisogramma anomola and is native to the northeastern United States and eastern Canada (although it has appeared in British Columbia, as early as 2001). Hazelnuts native to this region (Corylus americana) have proven to be more resistant to the disease (some are even immune) than the imported European hazelnuts (Corylus avellana). For Harry Lauder’s Walking Stick, a contorted hazelnut (Corylus avellana … Continue reading Eastern Filbert Blight On Harry Lauder’s Walking Stick
Horticulture For Home Gardeners 