Plant Healthcare and Disease Prevention

Be on the lookout for these regional spring/summer tree and plant diseases! Click to learn more and contact a certified arborist at Nels Johnson Tree Experts if you have any questions about your own trees and plants. 

Diplodia Tip Blight


Diplodia tip blight is a fungal disease that kills the tips of the branches of pines, and less frequently spruce and firs. In the blight stage, it can cause severe dieback and the fungus can grow into the stems and main trunk where it becomes a canker disease. 

  • Where to look: Austrian, ponderosa, mugo, red, and Scots pines
  • What to look for: A few brown needles at the tip of the current season's growth is the first evidence of tip blight.

Boxwood Blight 


Boxwood blight is a serious fungal disease that kills boxwood trees and shrubs. The blight typically spreads when people acquire infected bushes or trees and then plant them alongside or in place of their existing, healthy boxwoods.

  • Where to look: Boxwood 
  • What to look for: Spotted leaves, stem cankers and defoliation. The spots usually appear as light- or dark-brown, circular lesions that are often surrounded by a large yellow halo.

Apple Scab


Apple scab is a disease of apple and ornamental crabapple trees that attacks both leaves and fruit. Severely infected leaves become twisted and puckered and may drop early in the summer.

  • Where to look: Apple and crabapple trees
  • What to look for: The fungal disease forms pale yellow or olive-green spots on the upper surface of leaves. Dark, velvety spots may appear on the lower surface.

Cedar-apple rust


Cedar-apple rust is a fungal disease that requires juniper plants to complete its complicated two year life-cycle. From year to year, the disease must pass from junipers to apples to junipers again; it cannot spread between apple trees.

  • Where to look: Junipers, apple and crabapple trees.
  • What to look for: Pale yellow and orange pinhead sized spots on the upper surface of the leaves shortly after bloom. Heavily infected leaves may drop prematurely. Junipers experience large stem cankers that ooze when wet.

Important Questions and Helpful Tips for Selecting and Applying Fungicide

The spring season is a usually frustrating time for farmers and agriculturists.

During this time of the year, erratic temperatures are usually witnessed. This unfavorable temperature condition wreaked havoc on plants, thus, affecting their growth and development. The worst part is that they also aid the development of pest.

Another thing notable during the spring season is an increased amount of rainfall, thus, an increase in the amount of spruce and pine diseases. However, this record high precipitation makes applying foliar fungicides quite difficult.

Choosing and rotating your fungicide of choice can be quite challenging. Nels Johnson Tree Experts, your professional tree and plant health care company, brings you a couple of questions and tips to keep in mind while choosing and applying Fungicide during the spring season.

Helpful Tips for the Application of Fungicide:

Start Applying Foliar Sprays Early

Start applying foliar sprays for anthracnose on plants and trees such maple, ash, and oaks at a very early stage, precisely at a quarter leaf development. When applying treatment for anthracnose, lay more emphasis on the lower two-thirds section of the canopy. This will go a long way in reducing symptoms later during the growing season.

Cover New Growth with Spray

As we enter the growing season, the new growth of conifers will soon become rampant. This infers that the time to spray for botryosphaeria, rhizosphaera, and various other needle diseases will become necessary. For this reason, it is important to pay special attention while applying the spray. Ensure that all new growth getting are completely covered with the fungicide or spray.

Watch out For Lecanium Scale

Another disease that characterizes the spring season is lecanium scale. During the next couple of weeks, begin to watch out for this disease. Fortunately, lecanium scale can be managed by applying Transtect. As a result of the water-soluble nature of Transtect, it is very effective when used as a systemic treatment on scale insects. Transtect penetrates the plant quickly and distributes efficiently, thus, providing the most efficient way to treat scale insects systemically.

 Important Questions to Ask When Choosing Your Fungicides:

  • Will my work be able to support creating a single spray tank or route by making use of a single material or will do I have to mix different kinds of materials throughout the day?

  • Are there buildings, lawns, patios, or other hardscapes which require exceptional care while spraying materials made with copper?

  • What is the intensity of the pest infestation or disease on the tree, neighbors, and generally all over the region?

  • Will tank mixing a miticide be necessary?

There you have it! The above are some of the questions and helpful tips that need to be considered when selecting and applying a fungicide. Regardless of the type of plant, these questions and tips will guide you in choosing and applying fungicides perfectly.

For more information or professional helpful tips for choosing and applying fungicides for your plants, get in touch with us today at Nels Johnson Tree Experts. Our dedicated team of experts will be available to respond to you and provide a suitable response to your questions and concerns.

It's time for dormant pruning

Deciduous trees and shrubs are plants that drop their leaves generally during autumn or winter, and enter a dormant state. This is done mainly to conserve water that the tree needs to survive. Leaves contain small pores called stomata that allow for gas exchange to occur between the tree and the surrounding atmosphere, a process that is necessary for photosynthesis. However, these stomata also allow for a large amount of water to escape from the tree. By dropping its leaves, a deciduous tree or shrub can limit the amount of water that escapes from the plant during winter, allowing it to survive.

Trees can benefit from tree care services all year round. Procedures done during winter can lead to a healthier tree come spring. For example, applying a wide and evenly spread layer of mulch around a deciduous tree in early winter can help that tree bloom earlier and grow faster in spring. The layer of mulch acts as an insulator to the soil and roots of the tree, which remain active even in the winter. This extra layer of insulation reduces dramatic temperature changes in the soil, which can be harmful to roots.

Winter months also give arborists and tree care professionals a window of opportunity to perform dormant pruning. As the name suggests, dormant pruning is trimming that occurs during autumn or winter months (November – March), when deciduous trees are in their dormant state. With no leaves on the tree, arborists can easily examine the shape, structure, and condition of the tree’s branches. Contrary to what most homeowners think, dead wood is actually much easier to spot during winter. With no leaves to get in the way, dead wood can be easily spotted by changes in branch color, any cracks on the branch, fungus growth, or other symptoms such as the presence of buds. Once dead wood is identified it can be easily removed making the tree healthier and the property safer.

Not only does dormant pruning allow for easy identification of dead wood, it also allows for the overall structure of the tree to be examined. Professional pruning is more than the simple act of cutting out dead wood. Good tree care professionals shape the tree with pruning, providing long term health benefits. For example, if left alone or not pruned properly, trees can grow crossing branches in its crown. These crossing branches compete for the same space and resources in the crown, and by removing them a tree care profesional can increase both air flow and sunlight exposure to the crown as a whole. Proper dormant pruning can also improve the overall appearance and structural integrity of the tree.

Different styles and techniques of dormant pruning should be used depending on the condition of tree or shrub and the desired effect of the trimming. There are three main types of dormant pruning for trees and shrubs: selective pruning, renewal pruning, and rejuvination pruning. Selective pruning is the method most commonly used on trees. It is used to control the size and shape of the tree, as well as remove dead wood. First, obvious dead wood is removed. From there on, pruning is done branch by branch, removing branches that are not in healthy condition, or present a strucutral problem to the tree. Branches in trees should be removed at their base points, where they branch off from the trunk or another branch. If the branch is large or heavy enough, a 3-cut method should be used  to avoid any bark from being torn away with the branch. This method works by first making an upward cut about 1 or 2 feet away from the base of the branch. A downward cut is then performed, again 1-2 feet away from the base, intersecting with the first cut, effectively leaving a 1-2 foot branch stump, alleviating most of the weight of the branch. The final top-down cut can then be performed on the branch stump with no fear of torn bark or further damage to the tree. When conducting selective pruning, especially on shrubs, it is important to take breaks and step back from the plant, evaluating the effects of the pruning taking place, and when to stop.

Renewal pruning is performed most commonly on shrubs. Old shrubs with large branches and old growth can quickly become thickly overgrown, looking gnarly and unshaped. The goal of renewal pruning is to eliminate this old growth over time, and replace it with new growth. This is done in stages by cutting the oldest, most overgrown branches down to the ground, removing no more than a third of the plant at a time. In spring, new branches will grow to replace that third. Over a period of three years, removing a third of the old growth down to the ground each year, all of the old growth will be removed, and replaced (or renewed) with new, healthy growth.

Rejuvenation pruning is a drastic measure used only when a shrub is vastly overgrown or dense. In early winter the shrub is cut back entirely, to within an inch or two to the ground. The result may be surprising, but in spring new growth should begin to grow back, and within a few years the shrub will recover with new vigor. It should be noted that this method of pruning should be done only by professionals or after consultation by a professional, as not all decidous shrubs can survive the process, and the ideal timing of the pruning varies between species.