Question: My friend sprayed his apple tree with weed killer instead of fertilizer and we’re wondering if the apples will be edible. He threw away the weed killer container (he puts it in a container which he hooks to the hose to dilute it and spray it). Can you tell me if the tree will be OK and the apples will be good to eat?

This is a tough situation and you’re the fourth person to call about a problem like this in the past few weeks!

One of the most important rules about purchasing and using pesticides it to keep them in the original container. Never store them any other way. It’s just too easy for accidents like your friend’s, or even accidental poisonings, to happen when pesticides are kept in a different container.

The product he sprayed is a total vegetation killer, glyphosate (Killzall, Ultra-Kill, Roundup) plus another herbicide. The weed killer product remains effective for up to a year. I don’t know what its activity will be on the tree, but in the soil of the tree’s root zone it will be a problem. There is no way to know how the tree will do because of the extended activity of this spray. All you can do is give the tree good care (deep, infrequent watering — only once a week during the summer) and skip the fertilizer next year. Only time will tell whether the tree will be able to recover over the next year or two.

It may take up to a year before new grass will be able to grow in the affected area. Test plant a small area before you invest in reseeding the entire lawn under the tree. Or better yet, replace the dead lawn with something like bark nuggets so that it’s easier to water the tree more deeply and less often.

The product label specifies that this product shouldn’t be used near fruits and vegetables and warns that it shouldn’t be sprayed on the ground within twice the width of any tree canopy. Since it isn’t intended for use in the area of fruit trees, I don’t have any information about the safety of using the fruit. I called the customer service number on your product label and the agent couldn’t give me any safety information about the fruit on your tree.

I’m sorry I can’t give you a rosier opinion on using this year’s apples and on the future of the tree.

Question: How many chill hours do we get on average in Eagle Mountain?

Apple, pear and stone fruit trees like peaches and cherries need a period of chilling temperatures below a certain degree before their buds will develop normally. Chilling Hours are the units used to measure that cold period.

The total chilling hours for our area typically exceeds 1,200 hours each season. Different fruits or varieties may need different chilling periods, but the fruit trees along the Wasatch Front get the chilling hours they need well before the end of the winter.

Question: I have Kentucky Bluegrass; how tall should I mow my lawn with the temperatures at 90-100?

Kentucky Bluegrass is a cool-season grass that grows a little more slowly during the hottest part of the summer, waiting out the heat. There are a few things that you can do to help your lawn for the rest of the summer.

Mowing at a taller height encourages deeper rooting, shades the soil, and reduces weed seed germination. Mow your lawn at about 3-3½” tall; that’s the best height for the entire season. When your lawn has stopped growing and you’re ready to put away your mower for the winter, you can mow your lawn shorter (between 1½ and 2 inches tall) for its last mowing so that there won’t be long grass blades to mat down and encourage fungal growth during the winter and early spring.

Use a mulching mower. The dropped clippings return nitrogen to the root zone, slow down evaporation and cool the soil a bit. Dropping the clippings back into the lawn won’t cause your lawn to develop thatch.

Don’t mow your lawn if it seems drought-stressed. If the grass blades have a grayish hue and don’t rebound when you walk on the lawn, you need to water the lawn and give it time to recover before you mow.