This is the Q&A for the Yard and Garden show for June 23, 2017. Yard and Garden Live is a call-in radio show I do on KUTT 99.5 FM from 10-11:30 am and it will run through July 28, 2017. It can also be found on kutt995.com for online listening. If you missed a show or just want to read through the questions, I have written them all in my blog and will continue to do so throughout the season.
Guest Hosts: Mike Onnen, Manager for the Little Blue NRD & Donnie Engelhardt, Assistant Manager for the Little Blue NRD
If you enjoy reading my Q&A from the show each week, take my quick survey at: http://go.unl.edu/44qr and be entered to win a free plant book or some free UNL gifts.
1.The first caller of the day wanted to know if it was time to spray for bagworms yet this year and what to use for bagworms?
A. Yes, the bags have emerged. There is time for a couple of weeks yet to get them sprayed, just make sure you spray before the bags are 1 inch in length for best control. You can use any general insecticide for controlling bagworms such as sevin, eight, bifenthrin, tempo, or Bt can be used for a safer control method. Bt will not harm bees and other beneficial insects.
2. A caller has 2 large oak trees that when he parks his truck underneath it gets sticky from the aphids in the tree. What can be done to manage these?
A. The aphids are producing honeydew as an excretion and they do feed on the oak trees, but often this is not that damaging to the tree. You can spray for the aphids in the tree with a general insecticide, but if you give it a little time predatory insects will come in and kill the aphids. If you spray, you will kill the predators as well as the aphids. It is often not necessary to spray for aphids in a tree.
3. This caller has lilies that have grown too thick in her one garden bed. When can she divide these to transplant some in a new location?
A. This could be done this fall or you can wait and thin the lilies in the spring as well, either would be fine. I would advise against transplanting and dividing plants this time of year because in the heat, the plants don’t have enough roots to get to more water to keep them cool.
4. A caller has a weeping willow that has many leaves turning yellow and the tree is thinning. What would be wrong with the tree and how can it be managed?
A. This tree is likely dealing with environmental stress. There are not spots on the leaves to indicate a disease or damage that would be from insects. After viewing the photos, it is determined it could be due to improper planting as it looks too deep with no root flare. There may be stem girdling roots that would not be evident for a few years after planting.
5. How do you control ground squirrels in your yard?
A. There is a great publication on Ground Squirrels from the Internet Center for Wildlife Damage Management which shows how to set a trap for ground squirrels.
6. A caller has Iris, yucca, and prickly pear cactus that are all getting many weeds growing in and around these plants. The weeds include both grasses and broadleaf weeds. How can the weeds be controlled without injuring the desired plants?
A. The grasses can be sprayed with Grass-B-Gon or another similar grass herbicide. Unfortunately, there isn’t a selective herbicide that will kill broadleaf weeds and not kill broadleaf desired plants. For the broadleaf weeds, the best defense is to hoe the weeds out and mulch the garden in the future to hold the weeds back.
7. This caller has a plum hedge that has holes in most of the leaves throughout the hedge. The holes form initially as a brown spot and then a hole appears. What would cause this?
A. This is likely due to herbicide drift. There is no control for that, but if it is minimal it shouldn’t impact the hedge too much. However, multiple years of herbicide drift to the same plants can start to stress and in some cases kill the plants.
8. A caller has onions that have formed a soft, brown spot on the onions when they were dug recently. What would cause this?
A. This is likely a rot issue that developed from a pathogen in the soil. It is always best practice to rotate the crops. Also, ensure that you properly cure your onions before storage.
9. How can you control sandburs?
A. Crabgrass control in the spring will work for sandburs as well as foxtail and crabgrass. All of these are annual grasses.
10. A caller has tried to plant roses in the same location for a couple of years now and it seems like they grow to about 18 inches, bloom, but then die over the winter months. The are planted in a garden with rock mulch, watered with a bucket of water as needed, and were pruned off in March. Why can’t the caller get the roses to live longer than one year?
A. This sounds like mostly environmental stress to these plants. Rock mulches are hot and absorb no water, switch to a wood chip mulch to cool the roots and hold moisture. Watering should be done with a soaker hose or other type of sprinkler system. When a bucket of water is poured over the plants as needed, the water fills up the top pores of the soil surface quickly and then spread out rather than down. A slow trickle on the plants for a while each week to wet the soil down to about 6-8 inches will be more beneficial. Pruning of roses is best done in the middle of April once growth has begun further to ensure healthy wood is not also removed with the dead wood too early in the spring. Add extra mulch around the plants in the winter months, up to 4-6 inches deep in the winter months, then spread the mulch out to 2-3 inches deep during the growing season. Extra mulch in the winter will help protect the plants from inconsistent temperatures in the winter.
11. This caller wants to know when to dig up garlic? He also wants to know if bleeding hearts can be cut back now?
A. Garlic should be harvested in July after 30-50% of the leaves have died back. Harvest during dry weather and leave the bulbs on the ground to dry for a week before storing. The flower stalks of bleeding hearts can be removed, but the leaves need to be left on the plants to build sugars for next years growth and flower production.
12. How can grasshoppers be controlled if they are in the flower garden?
A. Any general insecticide will work for grasshoppers in flower gardens. Sevin, eight, tempo, bifenthrin, and others will work for flowers. When treating grasshoppers, it is also important to treat the grassy areas of roadsides and ditches where grasshoppers are often found.
13. This caller has grass growing in his asparagus patch. How can the grass be controlled?
A. Hand pull and apply a mulch to the asparagus patch. The earlier you get the mulch applied in the season, the better the control will be. Also, after harvesting is complete, the asparagus can be snapped off below ground level and Roundup or another glyphosate product can be applied as long as there is no green asparagus above the ground.
14. How can you control grasshoppers in the vegetable garden?
A. Sevin, eight, and bifenthrin are labeled for use in the vegetable garden. Also, remember to treat for grasshoppers in tall grasses along roadsides and ditches. Follow the PHI (pre-haravest interval) to know how many days after application necessary to wait to harvest the vegetables.
15. A caller wants to know when to transplant peach trees?
A. Fall or spring are both good times to transplant any trees.
16. The final caller of the day has a pond with moss or duckweed in it making it cloudy. What can be done to clean up the water?
A. Avast SRP is labeled for Duckweed and Copper sulfate can be used for Algae.