More recent landscape questions and answers

Horticulture

Live oak in Missouri

I fell in love with live oaks in Georgia. I understand they grow as far north as Virginia. Is there a way for me to grow a live oak here in southwest Missouri, zone 6?

Unfortunately, live oak is listed by most authorities as being hardy to zone 7 or 8, which means that it is likely to be damaged by temperatures below 10 degrees Fahrenheit. However, as you suggest, if seed is collected from the farthest north seed source possible, it may be possible to grow a seedling that may tolerate most of our winters. I am not, however, optimistic that a live oak hanging on by its toes in Missouri will ever look anything like the majestic specimens you saw in Georgia. It is best to stick with a native species and just enjoy the native trees in other parts of the country as you travel. A mature white oak is pretty majestic in my opinion.

Chris Starbuck
State Extension Specialist
Woody Ornamentals

Tomato plants die before end of season

For the past two years my tomato plants have died in late July or early August. I am going to send in soil samples, but how do I know which tests to order. I read that I should order the "regular" but the form doesn't allow for a space to tell the lab what the problem is. How should I proceed?

A soil test would help determine proper fertility levels and give specific fertilizer recommendations for optimum tomato production. However, for tomato plants that die before the end of the season, I would also suggest submitting a plant sample to the plant diagnostic clinic, where we can check the plant for diseases and give you management recommendations that will help prevent this from occurring in the future. Please see our Web site for more information on sample submission and fees. It is especially important to make sure the submitted sample has not yet completely died to ensure an accurate diagnosis.

Simeon Wright
Plant Diagnostic Clinic Coordinator

Sprouts re-sprouting

I cut down a Bradford pear tree three years ago. I still get suckers coming up in a five-foot radius around the stump. I tried gasoline and a popular herbicide to control them without success. How do I keep them from coming back?

You might try a product called Sucker Stopper, manufactured by Monterey Chemical Co. This product contains a growth regulator that inhibits sprouts from re-sprouting if they are sprayed immediately after they are cut.

Chris Starbuck
State Extension Specialist
Woody Ornamentals

Garden plants and flowers in Missouri

I recently moved to the Missouri from the East. What garden plants and flowers grow well in this climate?

Welcome to the challenge of gardening in Missouri. Have you experienced March in Missouri yet? In March temperatures swing through the extremes, and much plant material is lost. Often, our winters are not strong enough to initiate dormancy, and then we will plummet once or twice into the single digits, and plants just cannot take those extremes.

In the summer, tropicals do well as bedding plants and in containers. They love the heat and come on strong in July when everything else is going into a heat survival mode.

The best references for plants that do well here are our horticulture guides.

Ornamental grasses are popular here -- they are fine with the heat and lack of water in the hot, summer months. And some are very attractive. Walking the University of Missouri campus will provide a great showcase of plants that do well in this area.

Also, the Missouri Botanical Garden in St. Louis is well worth a visit -- and their Web site has tremendous resources. Many people do not know that the Missouri Botanical Garden is ranked number two in the world behind Kew Gardens in London.

Mary K. Kroening
Horticulture Specialist

Yellow spots on hibiscus leaves

I was hardening off a healthy hibiscus tree. On the third day it presented with yellow spots on the leaves. Upon examination I saw tiny, smooth, seed-like things on the branches. They ranged from dark brown to tan. There were no noticeable appendages or movement. I sprayed with an all-purpose parasite spray and the next day I easily scraped them off. Can you tell me what they were?

From your description, it sounds like these could be scale insects on your hibiscus, but it is difficult to say for sure. It can be very difficult to identify a plant problem from a description.

The Plant Diagnostic Clinic can identify insects in addition to helping you with plant identification or disease problems. I suggest taking some photos or collecting a sample of the possible insects or material on a small branch and submitting them to the clinic for identification. Please see the online image submission instructions and then click on the image link for insect images submission at the right side of the screen to submit photos and required background information to the clinic.

Simeon Wright
Plant Diagnostic Clinic Coordinator