Question:
We have a ten-year-old Photinia hedge that is approximately six-feet tall. Previously, some of the plants died. The leaves began to wilt, then they turned brown and finally, the whole plant die. They were replaced and we thought the problem was corrected but now it’s beginning again. What do we need to do to correct whatever is going on before we lose the whole hedge?Answer:
Photinias that wilt, turn brown and then die are suffering from root rot.- Another tattle tail sign is that before the foliage wilts the leaf color fades. Instead of being a bright glossy green it's a dull, muted greenish yellow color.
- Excessive summer watering especially following a wet winter, poor drainage and plants that are planted too deep in the ground are the primary reasons for root rot. Similar problems occur with other ornamental shrubs like junipers, azaleas, ceanothus and grevilleas along with fruit trees such as cherries, apricots, peaches and others. Because of the age of the hedge, I’d suspect that excessive moisture is the reason for the decline
- Established Photinia does not require constant moisture from frequent waterings. Their waterwise so once every ten days to two weeks depending on the temperatures, April through October is sufficient. To accomplish this you may have to cap off the sprinklers around them and then hand water when necessary.
- By changing the watering pattern now, it may be many months before you see a noticeable change and then again you may not. You need to key on those plants that look healthy. With root rot, what's going on under the ground is not always apparent above the ground until later on.
Question:
I’ve applied a pre-emergent herbicide to an area where I wanted no vegetative growth. It has done a beautiful job of keeping the area weed free. But now, I’ve changed my mind and I want to plant grass. How long must I wait before sod can be installed?Answer:
Pre-emergent herbicides prevent weeds from germinating by killing the seeds with a temporary chemical barrier.- The barrier remains effective for varying periods of time. This information is found on the product label. In addition, you can physically break the barrier by cultivating or tilling. You’ll need to amend the soil prior to planting and this should do it.
- There is no waiting period after the barrier has been broken. Hence, you can lay sod immediately afterward. Also, sod is grass plants with roots. Pre-emergent herbicides will not harm rooted plants; hence, it’s applied directly to desirable plants.
- It would be a different story if you were sowing seed. Again, they control the seeds of desirable and/or undesirable plants.
- My biggest concern is not knowing what product you used. There are combination products available that contain a soil sterilant. These products kill the dormant seeds along with the actively growing roots of plants. Tilling or cultivating will not eliminate this barrier. They dissipate over time usually twelve to eighteen months. This information is critical to know so you avoid making an expensive mistake. (This information is found on the product label.)