Thursday, June 21, 2018
Home and Garden

Ask Dr. Hort: Sampling grapefruit best way to select variety for yard

Let taste buds decide on grapefruit variety

Q: With all the worry about citrus canker and citrus greening I'm trying to decide on a grapefruit tree for our yard in St. Petersburg. The Duncan seems too seedy and the Thompson does not produce until December. I'm leaning toward Marsh, Ruby Red or Flame. In your humble opinion what would be a good choice as far as disease resistance, care, and most importantly, taste are concerned.

Mike Bandera

A: When it comes to taste, only you can decide which grapefruit variety, Citrus x paradisi, electrifies your taste buds. Take this season to sample the different varieties to come up with your favorite choice. All ripen from November to May and all exhibit the same tolerance to diseases and insects.

Still the hands down favorite of grapefruit connoisseurs is Duncan, the most vigorous grower and producer, the largest size and by far the seediest (50 to 70 seeds per fruit) with white flesh. Marsh with white flesh or Pink Marsh and Thompson (pink flesh) are very juicy with a bit of a tart punch with zero to six seeds.

Ruby Red is the most widely grown grapefruit in Florida, with zero to six seeds, the flesh is dark pink to pale red and very juicy. Star Ruby has the deepest red flesh, zero to six seeds, is very juicy and sweet, is slow growing and very bushy, but is the least cold hardy of the varieties.

And last but not least, Flame has deep red flesh, zero to six seeds, very juicy and excellent sweet flavor.

If you like grapefruit, you just might like pomelo's, Citrus grandis (Citrus maxima), the grandfather of grapefruit, with white to pink flesh and fruits 7 to 12 inches.

If you still can't make up your mind, you might get lucky at Jene's Tropical Fruit, 6831 Central Ave St. in St. Petersburg, and land a "cocktail tree" with multiple varieties grafted onto a single tree.

Happy hunting!

Sunflowerlike plant probably causing dog's seizures

Q: Attached are photos of a sunflower-like plant and a weed that is common in my yard. Recently, one of my dogs has taken to having seizures and I have noticed him chewing on the leaves of both of these and suspect one or both may be toxic. I tried finding a match online, but could not succeed. Do you happen to know what these are? They will grow up to 15 feet or so and easily takes root from just a branch.

The little weed has fine white runners that go just below the surface to other clumps of the green leaves.

Bob McKeon, Dunedin

A: The tall flowering plant is Bolivian sunflower, Tree sunflower, Honduras sunflower, Shrub sunflower and others, Tithonia diversifolia, a fast-growing plant that can be propagated by just a chunk of the hollow stem.

If not maintained, it can get a bit out of hand. The following link gives a good description, o Pesticides have been made from this plant; perhaps it didn't agree with your dog. Talk to your vet.

The small weed with the white rhizomes is Florida betony or rattlesnake root, Stachys floridana. My colleague Andy Wilson, senior horticulturalist at the Pinellas Extension Service, helped with the identification of the Florida betony. As the plant matures, 1-inch- to 1-foot-long tubers form at the ends of the rhizomes that look like the rattles on a rattlesnake. This tuber is very hard to control. The following link shows many growth stages of Florida betony.

The tuber is edible and tastes like a mild radish and the tops can be cooked as greens, so I don't think betony is the cause of your dog's seizures.

So, a big weed and a small weed or a beautiful flower and an edible plant, it's all how you look at it!

Box elder bugs look bad, but do no harm

Q: Do you know what kind of bug this is? It only comes and swarms the two trees in my front yard. Eventually they grow black wings.

Patricia Ardizzone

A: The dastardly little swarm of insects are box elder (Acer negundo) bugs, that are attracted to species of maple that doesn't grow here. However, they will feed on other maples, ash trees and others.

Your picture shows their juvenile form, red and black, but as they age they appear greyish-black and about 1/2-inch long and a 1/3-inch wide with three tiny red lines and look more like a stink bug of which they are a cousin. Squash one and you'll get the message.

The good news is, they don't hurt anything. You may see them en mass on your garage door or side of your house, somewhere in the sun. After several days as they continue to molt (get bigger), they sprout wings and fly off into the sunset, not to be seen here again until about this time next year.

Killing cherry laurel requires some work

Q: I have a problem with the invasive cherry laurel. About a dozen of them range in size from 3 to 8 feet. How can I kill them (roots included)?

Barbara Surprenant, St. Petersburg

A: To eradicate your pesky young cherry laurel trees Prunus caroliniana, cut them to a 6-inch stump, strip the bark and paint with products containing triclopyr such as Ortho Brush-B-Gon or Bayer Advanced Brush Killer Plus.

Fungi likely suspect in lack of mangoes on tree

Q: We had this mango tree since 2001. It is on the north side of a larger Loquat tree. Every year it flowers, but only keeps one fruit a year and it does not taste good. Is there something we can do so it can bear fruit?

Joseph DeBono, Dunedin

A: There are hundreds of varieties of mangos and some have a turpentine smell, so the flavor is part of the variety. The fruit setting problem has more to do with several fungi collectively called anthracnose which kills the flower before it sets a fruit.

The parasitic fungi turn the flower stalk black, killing the flowers before fruit can be set. The anthracnose fungi also produces black spots on the fruit later in the season which begin rotting the fruit. To retard the growth of the fungi, spray the creamy-white blooms with copper or neem oil weekly through the blooming season. Also, prune branches where disease has already claimed the flowers.