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.

The Noises of August by Donna Duffy

Cicada, photo courtesy CSU Extension

You’ve probably noticed that it's a noisy place out in the backyard with all that insect racket going on. Interestingly, only a few groups of insects communicate by rubbing their body parts together. What you are hearing are most likely cicadas, crickets and katydids. As you might suspect, it’s the males making all that commotion!

Aphids on Shade Trees By Joyce D’Agostino

Aphids photo by Joyce D'agostina

This summer I noticed some distinctive leaf curling on one of our shade trees. In checking it confirmed that there were aphids (lots of them) infesting this tree. The leaf curling in one sign of the damage that these insects can do. It is not only unsightly but left unchecked it can do damage to your tree.

Fortunately there are some solutions to reducing or ridding these insects from your plants. Aphids are very small, soft bodied insects. Using your hose on a hard stream, you can target the areas with a strong blast of water. This is very effective and if used regularly will reduce the population of these insects on your trees and plants. Check an area first with the water hose setting to ensure that you don’t damage the plant.  I noticed when I used this method that it did help remove a lot of the aphids from the curled leaves.  

Ladybeetles and Green Lacewings are also great natural predators of aphids. If you see these insects in your garden, moving them to the aphid area is very helpful.  Both of these insects are known to be able to eat a large amount of aphids, so make them a great non chemical use to help with aphid control.

Refer to these bulletins for more information on identifying and controlling the aphids.

http://www.ext.colostate.edu/pubs/insect/05511.html

http://www.ext.colostate.edu/pubs/insect/05594.html

http://www.ext.colostate.edu/pubs/insect/05550.html

Dividing Perennials by Donna Duffy

If your garden looks like mine, you probably have lots of overgrown perennials. The abundance of rain during the past couple of months has encouraged lots of plant growth. Take a walk around your garden and make note of plants that are ready to be divided.

Aphids Abound by Carol King

Aphids

Aphid Honeydew on Ivy

 Sitting in my backyard has become an unpleasant experience.  I have lots of deciduous  trees and they all seem to have a large crop of aphids.  One evening as I looked toward the sun, I could see the aphid “honeydew”  (poop actually) pouring down like a gentle rain! When I come in from outside, I feel as if I am covered with aphids!  Is there a variety that feeds on humans?

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.

Leafcutter Bees by Joyce D’Agostino

Leaf cutter bee injury

Have you noticed curious semicircular cut outs in the leaves of some of your plants? This might mean that the busy Leaf Cutter bees are at work. 

Recently I noticed these cut out shapes on the leaves of some of my Alpine Strawberry plants. In researching more about them, I found that these bees are a beneficial insect, even though they may be doing some damage to your plants.

Leafcutter bees (Megachile spp.) are considered one of the important native insects here in the Western United States. They are solitary bees, meaning that they don’t live in a hives as do the social honeybees, but they are still very valued as a pollinator. 

When they make the cut and remove the leaf from your plant, it is not for a food source but used to build their nest cells. When they form their cell home, they then line each leaf cell with a mixture of nectar and pollen. The female bee lays an egg into the cell and seals it shut, which produces a secure environment for the eggs to develop. Leafcutter bees make their nests in soft rotted wood but they don’t cause damage to homes or other wooden structures. 

Happy Fourth of July!

Plant fireworks from scribal.com

Happy Fourth of July to all our favorite gardeners!  Here's a link to some amazing plant fireworks.

http://scribol.com/environment/10-most-amazing-natural-fireworks-on-earth

Identifying Poison-Hemlock by Audrey Stokes

Poison-Hemlock (Conium maculatum).

Scientists recommend that you learn to identify and avoid plants that produce dangerous toxins. Your life may depend on it! Each year dozens of people die or are sickened by weeds they didn’t know would cause them harm. Gardeners and outdoor enthusiasts need to be well-informed in order to stay safe. Recently in Larimer County, a dog died from ingesting water hemlock. http://kdvr.com/2015/06/30/dog-eats-poisonous-plant-dies-within-1-hour/

Why are some weeds poisonous?  Most plants produce their own naturally occurring pesticide to deter predators so they won’t be eaten. No plant could survive without producing some defense mechanism. Most lists of Colorado’s toxic weed species that I researched were topped by the very dangerous Poison-hemlock (Conium maculatum). I found this especially alarming due to the fact that I have this weed growing on my property!  Originally imported from Europe as an ornamental plant, it has spread rampantly across North America.

Downy Mildew on Sunflowers by Donna Duffy

I always grow a few sunflowers at the edge of my yard every summer. They are a great conversation piece and a delight to the neighborhood kids and birds. Because of the rain, I got the seeds started late this year and they are up about 3" this week. I was checking them out and noticed a white fuzzy substance on the bottom of the leaves on two plants. After some research, I discovered this is Downy Mildew.

Snakes in the Garden by Donna Duffy

Every summer, I am greeted by garter snakes in my garden. I really do like having them there, I just don’t like to be surprised by them. Last year I was on hands and knees, reaching deep into some overgrown perennials, pulling out dead leaves and stems. When I pulled my hand out of the darkness, I discovered my fingers were wrapped around a snake. It wasn’t pretty for either of us: the snake went flying through the air and I ended up on my back. 

It was one of Colorado’s most common snakes, Thanmophis elegans, or the Western Terrestrial Garter Snake. Here are a few facts about this harmless snake from Colorado Herping.

Gardening Power to the People: Trellis / Vertical Gardening by Ed Powers

Watch this 4-minute video by Ed Powers, Jefferson County Master Gardener, about ideas for trellising and vertical gardening. Thanks, Ed!