Ponderosa pines, spruce may exhibit ‘winter burn’ by Colorado State Forest Service

A frost-damaged tree. (Courtesy of Colorado State Forest Service)

Ponderosa pines, spruce may exhibit ‘winter burn’ by Colo State Forest Service

A cold snap in October, coupled with last week’s extreme temperature fluctuations, injured ponderosa pines, other pine species and spruce trees in the Douglas and Elbert county areas, including Castle Rock, Franktown, Parker, Elizabeth and Kiowa. With warm weather preceding winter last year, the trees did not have the chance to transition into dormancy before freezing occurred. Large shifts in outside temperatures last week exacerbated the damage.

Check Your Turf for Snow Mold by Donna Duffy

Photo by Donna Duffy

Snow mold is a fungal disease that appears in late winter/early spring as the snow melts. Due to the prolonged snow cover this winter, there’s a good chance that you may find some patches of snow mold on your turf. I found several large and small patches when I walked around the (finally) snowless yard this morning.

Fall Needle Drop by Mary Small

Fall needle drop on Black Hills spruce, photo by Donna Duffy

Spruce trees often get attention in the fall. Their inner needles turn yellow or brown and drop off. To put your mind at ease, it’s not unusual for these conifers to shed interior needles beginning in late summer and continuing well into fall.  This is normal evergreen behavior. 

Fall Invaders: Insects in the Home by Mary Small

Box Elder Bug Photo clemson.edu

When days shorten and temperatures become chilly, folks often find uninvited guests – insects and their relatives- sharing indoor quarters. Although annoying and even startling, these creatures are just trying to hunker down for winter. They need to find shelter where temperatures hover between 40 and 50 degrees F. The west and south sides of a home can provide warm places to hang out as they search for prime real estate. They don’t need much of an opening on the home exterior to find it, either.  Many can squeeze into quarters using an opening the width of a credit card!

The best way to manage the intruders is to keep them out in the first place.  Look for exterior openings around windows, doors, etc., and caulk them. Examine door sweeps. Can you see light underneath the door? It’s time to replace the sweeps.  These steps will help keep the unwanted critters out and you’ll be increasing energy conservation, too!

Browning Evergreen Needles Normal by Mary Small

Photo by Carol King

Are your evergreens showing some browning and losing needles? Never fear! This is normal evergreen behavior.  It is not unusual for conifers to shed interior needles beginning in late summer and continuing well into fall.   In fact, all conifers (“evergreens”) including spruce, pine, fir, juniper and arborvitae lose their oldest needles every year. Contrary to what the name implies, “evergreens” are not really green forever. Their needles generally have a 2–4 year life span, although spruce trees live about 5-7 years. 

While needle loss occurs every year, the process is usually gradual, over a period of several weeks or even months, depending on species and weather. It’s so gradual, that you might not even notice the needle drop. Some species can shed needles in a fairly short period of time, making it look as though they’re in serious trouble. There is no need to treat evergreens for the condition.  

This fall and winter, ensure all evergreens are irrigated monthly in the absence of rain or snowmelt. Apply water so it reaches the absorbing roots.  For established plants, these are located a distance of two to three times the height of the plant away from it. For newly planted trees, apply water to the planting hole and just outside it. Always irrigate when the soil is unfrozen and able to absorb the water.  Studies show that fall-applied water has great benefit.  Roots are still active and can absorb water as long as soil temperatures stay above 40 degrees Fahrenheit.  

For more information about winter evergreen care check here.

Tomato Problems: Bacterial Diseases in Tomatoes by Mary Small

Photo by bitkisagligi.net

Photo by flickrhivemind.net

Moist weather in spring and summer can contribute to the development of bacterial diseases on tomatoes, just like it does for fireblight. The two diseases most often seen in moist years are bacterial speck (Pseudomonas syringae pv.tomato) and bacterial spot (Xanthomonas campestris pv. vesicatoria).

Leaf symptoms look the same for both diseases. Small water-soaked spots form and grow to about 1/8” in size with yellow halos. The centers are light brown and often tear; yellow halos are common. On more mature plants, infections are concentrated on the older foliage. Spots may also appear on the fruit pedicels.

Common Garden Diseases and Solutions by Mary Small

POWDERY MILDEW- White or gray, flour-like substance on leaves, stems, flowers. Thin plant if growth is dense. Keep water out of plant canopy or apply it when it will dry fast. Apply sulfur or potassium bicarbonate or horticultural oils at first sign of mildew.










EARLY BLIGHT(tomato)- Lower leaves yellow; spots of concentric rings found on lower leaves. Keep water off foliage, or apply when it will dry fast. Chlorothalanil fungicide may be applied at first sign of infection.











FIREBLIGHT(crabapple)- Stem tips brown, bend over like shepherd’s crook and shrivel. Drops of bacterial ooze on branches. Prune branch 6-12 inches below visible signs of infection. Treat pruning tool between cuts with 1:9 bleach mixture or rubbing alcohol. (Clean tools when done.) Thin tree branches. Avoid over-fertilization.












CYSTOSPORA CANKER(aspen, cottonwood)-Sunken discolored areas on trunk and/or branches. Dark “pimples” found in cankered area. Branch dieback. Prune out affected branches below visible signs of infection. Keep tree healthy.










LEAF SCORTCH-Leaves brown on edges and in between veins. Often found in hot dry weather. Apply water to plant’s root zone during hot dry weather or when scorch appears.

Ascochyta Leaf Blight Damages Lawns by Mary Small

Aascochyta Leaf Blight in Bluegrass

Cool moist weather followed by hot dry weather often spells Ascochyta leaf blight on turf. The fungal disease kills leaf blades, creating irregular patches of straw colored turf. Fortunately, Ascochyta does not kill the crowns or roots of plants, so they will eventually recover within a couple of weeks.

To manage the disease, mow lawns 3 inches tall, making sure mower blades are sharp. (Dull mower blades create ragged tips on grass plants, providing the fungus more entry points.)

Keep the turf evenly moist. Check sprinkler heads to make sure they are working correctly, are not clogged, tipped or broken. It's better to water deeply and infrequently. Shallow watering encourages shallow rooting which makes plants more susceptible to drying out. Too much water in poorly drained soils can increase disease development. For more information about Ascochyta, see this CSU Extension fact sheet.

Watch Your Lawn for Snow Mold by Mary Small

We have had  snow in the Front Range urban areas this winter, and snow mold might be a problem, especially in areas where snow is very slow to melt.  If you see evidence of it in your lawn, here's what to do.

Snow mold is a fungal disease that develops when snow falls on unfrozen turf and remains there for long periods of time. The most severely damaged grass is found adjacent to driveways (where large piles of snow accumulate from shoveling) or where there are snow drifts.  Snow mold fungi thrive in temperatures just above freezing, conveniently provided by the long-lasting snow cover!

Brown Needles on Pines May be Due to November's Cold Snap by Mary Small

Photo by CJ Clawson

We are starting to see the first damage to plants caused by the unseasonably cold weather in November. Many evergreens, particularly pine, are now showing injury from the rapid and sustained drop in temperature. Needles are turning a straw to red brown color, depending on the species and location.  Warmer, southern sides of trees are especially hard hit, since those areas had not yet developed complete winter hardiness. 

Photo by  CJ Clawson

Plants develop the ability to withstand cold winter temperatures in response to decreasing daylight and other signals. One of the signals includes exposure to gradually decreasing temperatures. And November’s cold spell was anything but gradual. We descended from early fall temperatures into mid January ones! The temperature dropped 50 degrees in a few hours.

 What can be done now? Water all evergreen root systems monthly in the absence of rainfall or snowmelt.  It won’t reverse the process – the brown needles won’t turn green again- but it will keep healthier portions of the plant hydrated. 

It will likely be mid-spring 2015 before we can begin to assess the true damage from the cold. And like a similar Halloween freeze of 1991, injury may continue to appear for a couple of years. 

Spotted Wing Drosophila Found in Colorado Fruits by Mary Small

Mushy Raspberries Infested with Spotted Wing Drosophila

The spotted wing drosophila is a newer pest in Colorado.  It was first reported in the state in 2012 and has been found in many counties.  The insect is a fruit fly that attacks fruit crops including raspberry, black raspberry, strawberry, blueberry, peach, cherry and grapes. They are particularly damaging to later ripening fruit.

One difference between it and other fruit flies is that the female can lay eggs in ripening fruit. (Most fruit flies attack fully ripened fruit.) When fruit is ripe and ready to be picked, it can already be infested. That’s because the female has a sclerotized (hardened), serrated ovipositor (egg laying structure). She can pierce fruit that has not yet been softened in the ripening process. The eggs hatch into tiny maggots that quickly convert fruit into a mushy liquid mess.

Control is difficult. Fruit should be picked on a regular basis and all fruit that’s dropped to the ground should be collected and discarded. The fruit growing area should be cleaned up of debris in the fall. Insecticidal sprays are applied to the crop on a regular basis once the insect has been reported in your area.  Please see this publication for suggested products. Treat crops in the early morning or in the evening when bees are less active to avoid harming them.  Read the label to determine when you can harvest the crop after treatment as this varies from product to product. 

Fire Blight Arrives in Our Trees! by Mary Small

As if trees didn’t have enough trouble from last summers’s hail, fall's damaging freezes, and a late spring, some have now developed fire blight!  This bacterial disease is common on crab apple, apple, mountain ash and pear. 

Warmer than average temperatures during blossom time creates ideal conditions for disease development. If rain falls at the same time, its spread is rapid.  And guess what?  This spring was just perfect, if you were fire blight bacteria!

Large Miller Moth Population Expected by Mary Small

Euxoa auxiliaris Miller Moth

According to CSU Extension Entomologist, Dr. Whitney Cranshaw, “miller moth” numbers will be above average. Because the numbers of their caterpillars found in crops and other locations this spring, the moth numbers may be way above average. 

How much of a nuisance they will be is dependent on moisture and numbers of flowering plants around. Moisture has been good, contributing to the development of flowering plants. While last week’s freeze may have damaged some flowers, they are still abundant and will be attractive to the moths. Moths feed on nectar in the flowers.

Flowering plants most often visited by miller moths in our area include lilac, cherries, spirea, cotoneaster, horse chestnut, raspberry and Russian olive. Dark and dense plants such as cotoneaster, spruce and pines are most used by miller moths for shelter around homes.

The moths become a problem for humans when they accidentally enter homes.  During the day moths seek shelter in cracks and crevices around homes, in door entries and near windows.  At night, the moths become active and may be attracted to indoor or exterior lighting.

The major infestation is not expected for a few more weeks, about mid-June.
For detailed information on miller moths, including deterring them from your home, see this information.

Lawns Struggling as Spring Gets Underway by Mary Small

It’s not that unusual for lawns to look a bit tough right now, especially when MotherNature hasn’t been cooperative with moisture! What’s a person to do?
First, try to figure out what is causing the lawn problem.  Look at it as a whole and see if you can pick out a pattern to the damage.

A colleague of mine stood took this picture from her home’s second floor window. You can see that some areas of the lawn are brown and some are green.  The damage is happening in swaths, not small spots or circles. This pattern is pretty typical of poor sprinkler function and it means that the sprinkler system needs a closer look. (Especially note the foreground and the area near the raised bed in the background.)The problem could be that heads are plugged or partially plugged, so aren’t applying enough water. They could be tipped due to the freeze/thaw cycles from winter. Maybe the head is a bit high and was dislodged during aeration or mowing. But you won’t know until you look at the sprinkler heads and check sprinkler delivery.

Winter Damage in Colorado Evergreens by Mary Small

Many conifers aren’t looking too great right now. Much of the problem is related to dry fall and winter weather over the last couple of years.  Fall and winter months are typically dry, but these past couple of years have been especially dry.  How does that affect these plants?

Although trees and shrubs “go dormant” in the fall, the root systems of these plants still function as long as soil temperatures hover around 40 degrees.  Roots need water  to function properly and their source for that is either Mother Nature or irrigation that we provide.  No water during this period stresses or kills roots through dehydration. 

Evergreen leaves can continue to transpire, that is, lose moisture to the surrounding environment, on warm sunny days, even in the winter.  This is a normal leaf function, designed to keep the leaves from overheating, kind of like our perspiration. 

Lilac Ash Borer Does Not Equal Emerald Ash Borer by Mary Small

 

Lilac Ash Borer Damage in Ash

I was recently sent this photo and asked if I thought this could be emerald ash borer damage. Apparently a lot of ash trees in the neighborhood have similar injury.

Note D-shaped holes

One hole looks like a D, which could indicate a flatheaded borer such as emerald ash borer. (But flatheaded apple tree borers can also infest stressed ash.) Consider too, that lilac ash borer creates irregularly round exit holes and the rest of the holes in the picture are round-ish. The D shaped hole also is ragged around the edge, which is not typical of the flatheaded borers mentioned above.

Jeffco CSU Extension Colorado Master Gardeners: 2013 Highlights by Mary Small

Colorado Master Gardener volunteers in Jefferson County actively engage Jefferson County residents to foster successful gardening. A dedicated corps of 110 volunteers brings a variety of projects to life. In 2013, these energetic volunteers donated 6944 hours to CSU Extension. In business terms, that’s the equivalent of almost 3½ full time staff! In dollars, that volunteer service is worth $153,740. Following are descriptions of some of the major outreach projects which resulted in 10,338 direct contacts with Jefferson County citizens.

Beekeeping 101

Public Gardening Classes – CMG volunteers trained in public speaking presented classes on a variety of gardening topics throughout the year. One of the most successful projects in 2013 was the Backyard Food Production Classes. Colorado Master Gardeners and staff in Jefferson County developed a class series that studied successful backyard food production. Topics covered included Small Fruit Production, Growing Heirloom Vegetables, Biointensive Garden Design, Starting Your Own Plants from Seed, Soil and Amendments, Irrigation, Mapping, Planting, Season Extenders and Backyard Beekeeping. Three hundred seventy two (372) citizens attended. Approximately 1/3 of the audience were first time gardeners. 

Fall Needle Drop Is Normal in Evergreens by Mary Small

Photo by Carol King

Spruce trees are getting a lot of attention this fall. Their inner needles are turning yellow or brown and dropping off. To put your mind at ease, it’s not unusual for these conifers to shed interior needles beginning in late summer and continuing well into fall.  This is normal evergreen behavior. 

In fact, all conifers (“evergreens”) including spruce, pine, fir, juniper and arborvitae lose their oldest needles every year. Contrary to what the name implies, “evergreens” are not really green forever. Their needles generally have a 2–4 year life span, although spruce trees live about 5-7 years. 

While needle loss occurs every year, the process is usually gradual, over a period of several weeks or even months, depending on species and weather. It’s so gradual, that you might not even notice the needle drop. Some species can shed needles in a fairly short period of time, making it look as though they’re in serious trouble. And environmental problems, like drought, can make needle drop happen more quickly than it would if the tree was healthier.

Heavy Rainfall Causes Tomato Problems by Mary Small

Fruit Splitting Caused by Too Much Water photo by Mary Small

There are some strange things happening to my tomato plants. They are wilting, some have blossom end rot and some fruit is splitting open.  Don’t plants wilt when they need water? Isn’t blossom end rot due to irregular watering? Well, yes, but………

Plants can wilt when there’s excess water around, like the 6 inches that fell on my garden. Soil contains pore space between the mineral and organic particles, some holding water and some holding oxygen.  But when a lot of water is applied to the soil, it drives the oxygen out.  Soil oxygen is needed by plants to perform various functions.  No (or low) soil oxygen damages or kills roots and these damaged roots can’t absorb nutrients and water.  So plants wilt. 

Mid-Summer Leaf Drop by Mary Small

Tree owners and those responsible for maintaining trees often observe leaf drop occurring in mid-summer. Sometimes the number of leaves falling appears excessive, but in reality, the number of leaves lost is small in comparison the overall number of leaves in the tree. Some suggestions for the cause or causes of mid-summer leaf drop can include: drought; adjustment to summer conditions; inner leaf drop and shading.

Drought: Trees may lose as many as 10% of their leaves during a drought without being irreversibly affected. Typically, once drought conditions are in place, leaves begin to drop and continue to drop for the extent of the drought period. While a tree uses leaves to make food, this amount of leaf loss does little or no harm, and may actually be helpful to the tree. By shedding these leaves the tree loses less water through transpiration

Adjustment to summer conditions: Sometimes trees just make too many leaves! When cool moist spring weather turns to hotter, dryer summer conditions a number of leaves may drop suddenly. This is called "physiological leaf drop" and does not harm the plant's health. This leaf drop is simply a defense mechanism from further injury. When weather conditions are hot and dry, trees can take up an immense amount of water. If that water is not in the soil to support the root system the tree shuts down to preserve the moisture needed for continued life. This means eliminating the loss of water…which happens to be through the leaves.

Inner leaf drop: The observer should look carefully at the tree. If the falling leaves are from the inside of the tree they may have been "shaded out". Inner leaf drop occurs when the leaves on the outside and top of the tree are so thick that the leaves inside the tree do not receive enough sunlight. After such leaf drop, the larger branches inside the tree and close to the trunk look bare. Inner leaf drop is normal and not harmful.

Shading: If leaves can be lost due to shading from within a single tree, then it follows that leaves can be lost when an entire tree is shaded. Trees are living things and a tree may grow so large that it begins to cast shade on another tree which was once in sunlight. The smaller tree no longer receives enough light to support its leaves which begin to drop. Another form of shading occurs when closely planted trees grow so large that they begin to shade each other on the sides that face each other. Often, this leads to leaf loss on the sides of the trees where they are in close contact or are intermingling branches.

Adapted from: Ohio State Buckeye Yard and Garden Online and Brian Pugh, Oklahoma State University