Cool, Wet Spring Causing Leaf Diseases

Leaf diseases have become a concern this spring because of the cool, wet weather, and rain provides an efficient way for fungal and bacterial spores to spread. Fungal disease symptoms generally include irregular brown, yellow or black spots on leaves. If left unchecked, branches can also become infected. As the season progresses, the spots may turn into holes in the leaves.

There are several strategies to prevent and manage leaf diseases:

1. Manage irrigation systems so they do not spray the foliage.

2. Irrigate during daylight hours where possible, when foliage can dry quickly.

3. Clean up infected leaf litter in the fall, and prune out heavily infected branches.

4. Consider the role plant genetics play in diseases, and avoid planting certain species such as sycamore (Platanus spp.), aspen, English hawthorn and peonies since they are highly susceptible to foliar diseases.

Most chemicals used to control plant diseases are best used as a preventative. For most diseases that have been seen this year, the correct timing for spraying is just before, or just as, the plant is leafing out.

As of mid-June, diseases still common along the Wasatch Front include fungal anthracnose in maple, oak and especially sycamore; powdery mildew on many trees and perennials like apple and peony; coryneum blight (shot-hole fungus) in stone fruits and related ornamentals such as purple leaf sand cherry; and fire blight bacteria in apples, pears and related ornamentals such as pyracantha, hawthorn, serviceberry and cotoneaster.

The best time to prevent anthracnose is in early spring with a registered fungicide. As drier weather sets in, fungicide sprays to control anthracnose or coryneum blight are less effective. Make spray applications when leaves start to emerge. Repeat applications may be necessary if the weather stays wet and cool. The optimal time to treat coryneum blight is just after petals fall from the flowers in the spring. Another excellent time is in autumn when about half the leaves have fallen.

Powdery mildew on trees and shrubs can be suppressed in early spring with a dormant oil application just before leaves emerge. After leaves are formed, either a summer-weight horticultural oil or neem oil can be sprayed according to the label as a continued preventative until dry weather sets in. Where there is risk for severe infection based on history, spraying in the spring, according to label directions, with a registered fungicide is often warranted.

Fire blight is bacterial and usually enters a plant through open flowers or through wounds from rain or insects. Infected wood turns black or dark brown in apples, looks burned and may form a shepherd’s hook on young branches where blossoms were. Once an infection occurs, pruning is the only way to remove it. Make pruning cuts into healthy wood 6 to 12 inches beyond where symptoms occur. Pruning tools must be disinfected with rubbing alcohol, hydrogen peroxide or disinfecting wipes after every cut. If fire blight is not pruned out, it will eventually kill the plant. Chemical sprays for fire blight are for prevention only and include agricultural antibiotics such as streptomycin or copper solutions. They must be sprayed when susceptible plants are flowering in the spring. Repeat applications may be needed during this time and will not harm pollinating insects.

It is also important to remember that not all discolored spots or holes in leaves are due to fungal or bacterial diseases. Nutrient deficiencies, such as severe iron deficiency, can cause leaves to get dead spots. Weather events, such as hailstorms and wind, account for most of the leaf damage on plant leaves.

For further information about anthracnose, visit the USU Extension Pest Lab website.

For further information about coryneum blight, see the USU Extension fact sheet.

For further information about powdery mildew, see the USU Extension fact sheet.

For further information about fire blight, see the USU Extension fact sheet.

By: Taun Beddes, Taun.beddes@usu.edu Mike Caron, Mike.caron@usu.edu




Living in Snake Country – Six Things to Consider

For many, the sight of a snake is what nightmares are made of. Unfortunately, all too often Hollywood and has taken advantage of people’s fear of snakes for profit. Some companies may also market products or services that are ineffective at repelling snakes, and in some cases, these products may actually increase the risk to people and pets.

The U.S. Centers for Disease Control estimates that 6,000 to 8,000 people are bitten by venomous snake annually and that up to six snake bite victims may die. Annually, an estimated 90 human deaths occur from various venomous animal encounters. The stings and subsequent anaphylaxis from bees, wasps and hornets are responsible for over 90% of the reported human deaths.

Of the 31 species of snakes found in Utah, seven are venomous. These are commonly called pit vipers because of the pit located between their nostrils and eyes. Most pit vipers found in Utah also have tails with a series of rattles, hence the name rattlesnake.

All snakes are classified as non-game animals and are protected by Utah state law. A person cannot lawfully collect or possess a live wild snake without receiving a Certificate of Registration from the Utah Division of Wildlife Resources. When there are human, domestic pet and livestock safety concerns, a venomous snake may be killed without a certificate.

Because most snakes in Utah are non-venomous, most human-snake encounters are generally not dangerous. However, if you encounter a venomous snake and are bitten, the consequences could be serious. Consider these tips.

* If you encounter a snake, your best strategy is to leave it alone. Every year, hundreds of want-to-be herpetologists and snake charmers are bitten when they try to capture or kill a snake. Even dead snakes have been known to bite by reflex action. More than half of the reported snake bites were a result of someone trying to handle or kill the snake. It is always best to leave the area if you encounter one.

* When rattlesnakes are encountered or disturbed, the rapid vibration of their tails will make a

characteristic rattling sound to warn the intruder of their presence. However, not all rattlesnakes will “rattle” when disturbed. For this reason, when you are in rattlesnake country, you must pay close attention to where you walk, sit and place your hands. Rattlesnakes can be found throughout Utah in sagebrush, pinon-juniper woodlands, sand dunes, rocky hillsides, grasslands and mountain forests.

* If you hear a rattlesnake “rattle,” stand still until you can locate where the sound is coming from. Do not try to jump or run. If you do, you may end up within the snake’s striking range.

If bitten by a venomous snake, do not engage in physical activity such as walking or running. Do not apply a tourniquet to the area above the wound and do not apply a cold compress to the bite area. Do not cut into the bite. Do not take anything by mouth, including stimulants or pain medications, unless instructed by a physician. Do not raise the bite area above the level of the heart, and do not try to suction the venom, as doing so may cause more harm than good.

All venomous snakebites should be considered life threatening. When someone has been bitten by a venomous snake, time is of the essence. If possible, call ahead to the emergency room so anti-venom can be ready when the victim arrives. Until then, keep the victim calm, restrict movement and keep the affected area below heart level to reduce the flow of venom. Wash the bite area with soap and water. Remove any rings or constricting items, as the affected area will swell. Cover the bite with clean, moist dressing to reduce swelling and discomfort. Monitor the victim’s vital signs (pulse, temperature, breathing, blood pressure). If there are signs of shock, lay the victim flat and cover with a warm blanket. Get medical help immediately. If possible, bring in the dead snake for identification if this can be done without risk of injury.

* Bites from venomous snakes will almost instantly show signs of swelling and discoloration of the surrounding tissue. Other symptoms include a tingling sensation, nausea, rapid pulse, loss of muscle coordination and weakness. Also, bites from rattlesnakes will show two characteristic fang marks (punctures) as well as other teeth marks. Non-venomous snakebites are harmless, but there is still a risk of infection. If bitten, clean and sterilize the wound much like you would a cut or abrasion.

More information about snakes is available at WildAwareUtah.org




Gardener’s Almanac Checklist for June

It has been said that June is the gateway to summer. With that comes many opportunities to be out in the yard and garden. Utah State University Extension’s Gardener’s Almanac provides a checklist of tasks for June as well as links for tips and further information.

Tasks:

·Harvesting of asparagus spears should stop in early June to allow the fronds to form for the rest of the growing season.

·Prune tomatoes to open the canopy of the plant.

·Consider drip irrigation in the garden to conserve water.

·Consider planting sweet corn in the garden every other week (until early July) to extend the harvest.

·Prune spring flowering shrubs (those that bloom before June) after they have bloomed to encourage new flower buds for next season.

·Deadhead (cut off) spent blossoms of perennial and annual flowers.

·Thin the fruit of apples, peaches and apricots to approximately one fruit in every 5-6 inches.

·Apply a second application of pre-emergent herbicides in early June to control annual weeds in the lawn such as crabgrass and spurge.

·Turfgrass only needs 1-1 ½ inches of irrigation per week. Click here for irrigation needs in your area. 

Pests and Problems:

·Monitor vegetables and herbs for earwig damage.

·Protect ash trees with a registered chemical to prevent lilac/ash borer damage.

·Control Codling moth in apples and pears to reduce wormy fruit. For specific timing, see the Utah Pests Advisories.

·Treat for powdery mildew on apples when leaves are emerging (at 1/2 inch green) until June.

·Watch for insect pests in raspberries from mid-May thru early June. For specific timing, see the Utah Pests Advisories.

·Control the Western cherry fruit fly when fruit changes color from straw color to pink to avoid maggots in cherries.

·Control the Peach twig borer in peaches, nectarines and apricot trees. For specific timing see the Utah Pests Advisories.

·Monitor for damaging turfgrass insects. In areas previously damaged, consider a preventative (systemic) insecticide.