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Past Questions and Answers | August 2006

This month's questions concern:

Tomato Flowers Falling off
Tomato Suckers
Thinning Pumpkins
Plum Tree Suckers
Rose of Sharon Follow Up
Propagating Japanese Maple
Pruning Gardenias and Loropetalum
Dodder Vine
What's Eating my Petunias

Please scroll down to read the answers.

Question #1:  Tomato Flowers Falling Off!

Question:  My tomato plants bloom like crazy but I never get any tomatoes!! What can I do to keep the booms from falling off?

 Karen Gordon, Rockwall, TX


ANSWER:  Hi Karen,What you are experiencing is "Blossom-Drop." Tomatoes, peppers, snap beans, and some other fruiting vegetables will actually flower, but then fail to set fruit, and then the flowers die and fall off. It can be caused by the use of excessive nitrogen fertilizers or dry windy conditions, but the most common cause is temperature extremes. Tomato flowers fall off when the weather has taken a quick turn and it gets very cool, or very hot, or the soil is dry.

Tomatoes, peppers and beans can be touchy about the air temperature when it comes time to set fruit. If the night temperature falls below 55 F or rises above 75 F, or if the day temps are above 90 F, the pollen becomes tacky and non-viable. Pollination cannot occur. If the flower isn't pollinated, the bloom dies and falls off.

What you can do is try and improve the growing conditions.

Try and keep the moisture even in the soil. Don't let it get too dry. A good rule of thumb is to water when the soil is dry about 1 inch below the surface. Try mulching heavily to maintain constant soil moisture levels, and if your area is super windy, try and either plant them out of the wind, or create windbreaks.

Use a balanced fertilizer instead of one with too much nitrogen, so like a 10-10-10 or a 15-15-15, and if possible next year, plant your tomatoes a little earlier to avoid the high temperatures.

The good news is that fruit set will improve when temperatures level out. Also, you might want to change the variety you are growing next time and choose an indeterminate, or tall, variety which flower longer and more profusely.

Some other varieties to keep in mind that are more hot and cold tolerant are:

Cold Tolerant are: Stupice, Early Pick
Heat Tolerant: Hawaiian, and Solar Set

You can also put shade cloth over your tomatoes if it gets super hot. My sister does this because her tomatoes and peppers can get sun scalded in Montana.

Anyway, I hope this helps and good luck!

Question #2:  Suckers on Tomato Plants

Question:  What are suckers on tomato plants? I was told to pinch these off.

Colleen Fischer, Coloma, MI


ANSWER:  Hi Collen, suckers form at the "V" between the central trunk (stem) and lateral branches. If left on the plant, they will keep growing and usually produce fruit. It can be helpful sometimes to prune suckers out so the overall plant doesn't get top-heavy or produce more fruit than the plant can mature in time for Fall. You can let some of the suckers stay on if you want, as long as the plant is supported.

If your plants are allowed to sprawl along the ground, as I do with my cherry tomato plants, I never remove any suckers at all!

Suckers don't hurt anything, it's up to you what you, how you want your tomatoes to grow. Some additional information:

There are 3 different kinds of tomatoes. Determinate, indeterminate, and semideterminate.

Determinate tomatoes are bushy and get about 3 feet tall. Each side branch they produce, produces a flower cluster and therefore, possible tomatoes.

Indeterminate tomatoes produce a lot of suckers from the main stem of the plant. If conditions are good, they can flower and set fruit.

Semideterminate plants have habits of both.

If you have an indertminate tomato, it will keep growing, so you can stake and prune them. Just keep in mind, if you prune them, you will get fewer, but larger fruit.

Again, it's up to you.

Question #3:  Thin Pumpkins or Not?

Question:  We are growing pumpkins this year and my husband said that he thinks that we are supposed to take off some of the pumpkin blooms or the pumpkin starts to insure bigger and healthier pumpkins. What do you say? Thank you,

 Colleen Fischer, Coloma, MI


ANSWER:  Hi Collen, it depends on your goal. People who grow pumpkins to enter "largest pumpkin" contests only leave one pumpkin for the entire plant. That is so all the energy can go into getting as large a pumpkin as possible.

It doesn't hurt the plant to leave all the pumpkins on, but generally they will be smaller. They will still be healthy, leaving them on won't affect their health, but their size, can overall be smaller. So if you want fewer, larger pumpkins, you can remove some of the flowers. It you don't care about size, leave them all on.

Don't forget to lightly feed them at least once in the growing season with a 10-10-10 or a 5-10-10 balanced fertilizer to help them along.

I hope you enter your pumpkins in the contest I have on the site: I would love for you to win!

Question #4:  Suckers on Plum Trees

Question:  I have a two part question:

Question 1. My Santa rosa plum is sending out hundreds of new starts from it's roots. I chop them down, but they come back even more. What can I do to stop this from happening?

Question 2. Is this true of the roots that come up from the ground? I know about the suckers that come off the limbs. My problem is coming up from the ground from the roots.

 Debbie Ingamells,Estacada, OR


ANSWER:  Hi Debbie, I answered your two part question with two answers!

Answer to Question 1: Lots of trees produce suckers every spring, and even though you cut them back, the suckers will continue to come back all summer long, which can be very annoying.

I think you should try a product called Sucker Stopper. It prevents suckers from coming back after you have pruned them back. All you do, is after you have cut the suckers back, cover where the sprouts have been removed with Sucker Stopper.

Try and treat the sucker area before the suckers get 10 inches long. The earlier you treat them, the better.

Make sure you read the label carefully, and don't apply during bloom or fruit set because fruit set reduction may occur. On woody ornamentals, this isn't a problem.

Control usually lasts about 3 months.

Answer to Question 2: I hate to be the bearer of bad news, but yes, suckers can come from the roots! You will have to dig down and see where they are originating from, cut them off, and then carefully use the Sucker Stopper.

When putting Sucker Stopper near the root area be super careful because you don't want to affect the growth of the plant. It is a lot of work, but with consistency you will get rid of them.

Hang in there!

Question #5:  Rose of Sharon Follow Up

Background: Kim originally wrote in with a question about her Rose of Sharon bushes leaves turning yellow and wondered if she was watering correctly.

Here is her Follow Up Question: Thank you for answering my question on my Rose of Sharon. We water about every other day because it gets really hot and humid in MS. About how long do they take to really look there best it seems like some leaves are falling off, but the plants are getting taller, and new leaves are growing.

 Kim Missi, Saucier, MS


ANSWER:  Hi again Kim! Watering every other day is fine, as long as the soil has truly dried out and the plants need the water.

The first thing that comes to mind is, when is the last time you fertilized your plants? During hot and humid weather many times plants simply get rid of some leaves to help "lighten the load" so to speak.

If a plant gets stressed, it can try and lighten how much moisture it has to move to all its leaves, buy dumping some if them and making it easier on themselves. Feeding them regularly helps give them the nutrients they need to withstand tough weather conditions, like heat or even cold.

I would mulch with a good compost, not mushroom compost, but any other kind is fine around the base of the plants. Don't put the mulch too near the plant stem, you don't want to rot the plant out, just mulch around the root area.

I would try and keep them evenly moist, which it sounds like you are, an then feed with some hydrolyzed fish, mixed with kelp. You can get that at Neptune's Harvest, they have a website:

Kelp really helps plants that are stressed. You might also want to lightly prune the plants to help reduce the overall size of the plant.

So to recap, I would:

1. Check the soil to make sure the plants need water
2. Put a good mulch, an inch or two, around the plant bases
3. Feed with good organic fertilizers, including kelp
4. Lightly prune them to help get them through the summer

As to how long it will take for them to look good? If you do the above, I would expect to see improvement in 4 to 6 weeks.

Let me know how it goes. I always like to hear follow-ups.

Question #6:  Propagating Japanese Maples

Question:  I have a Japanese Maple bush and I was wanting to know is it possible to take a cutting off the one I have and root another one, and if so, how do I go about doing that?

 Regina Burnette, Morganton, NC


ANSWER:  Hi Regina, Japanese Maples are generally propagated by grafting. A few cultivars can successfully be grown from cuttings, but usually cutting-grown trees do not have vigorous roots and the trees fail to thrive.

Because cuttings are very hard to do, and are not very successful unless you are willing to go to a lot of trouble. There are two alternatives for you though.

1. Grow them from seed: Japanese Maples grow very easily from seed. You can collect some seed after the leaves drop. Bunches of ripe, winged seeds will hang from the branches before they fall. Rub the wings off, and put them in a plastic bag in the refrigerator with just a bit of slightly damp paper towel to maintain humidity until late winter.

Soak the seeds in some water before planting. Plant about a half-inch deep in a combination of peat and perlite. Not all the seeds will sprout, and the seeds that do will not always exactly resemble the parent plant, but take traits from both parents. You could even wind up with something new. It's not hard, and a fun project.

2. Graft them: This is not hard, but requires some practice and it might not be for you. I can't teach you how to graft via this forum because it has several steps, so I suggest you get a book at the library.

Use a side veneer graft in late August-September, and tie a plastic bag around the graft for a few weeks.

If it were me, I would try propagating from seed, or I would break down and go buy one at the nursery!

Question #7:  Pruning Gardenias and

Question:  I have several Gardenia plants and also Loropetalum plants. They are about 3 to 4 ft. tall and kind of spindly looking. I need to know when and how far to cut them back I guess, to make them grow bushier and fuller?

 Ruth Hefner, Pensacola, FL


ANSWER:  Hi Ruth, well both are great plants so I can see why you want them looking a bit fuller.

I am assuming that both plants are getting their required growing conditions met. For some specifics:

Gardenias: Gardenias like plenty of sunshine, but not searing heat. As for pruning them back, your Gardenias should be pinched back around late winter, early spring. I wouldn't take too heavy a hand with the gardenia. I would lightly pinch it back, like an inch or two, and make sure you feed it regularly.

I would feed it every two weeks during the spring and summer with half-strength acid plant food. In the fall reduce feeding to once a month.

The combination of a light pruning with regular feeding will make it nice and bushy in no time.

Loropetalum: The Loropetalum or Fringe Flower is a pretty tough plant. They like full sun to dappled shade, and can take any amount of pruning. They tend to flower in the spring, so I would prune it back after it is done flowering, around early summer. You could even do it now and you won't hurt it.

Fringe Flower can get to about 6 feet tall, so if your plants are currently about 3 to 4 feet, I would take about 8 inches off and shape it.

Also after pruning, I would start feeding it regularly with a balanced fertilizer like a 10-10-10 or 15-15-15.

Sounds like both plants, the Gardenia and The Fringe Flower just need a little extra feeding, and a light pruning and they should be looking really good in no time.

Question #8:  Dodder Vine

Question:  I have a threadlike vine that is growing in my Verticillata. It is an orange-yellow and wraps around the stems and appears to grow out of no where. It has no roots and I have been pulling it off the plant. What can I do to get rid of it?

 Renae Learn, Denver, IA


ANSWER:  Hi Renae, it sounds to me like you have Dodder Vine. Does it look like the picture I have posted here? Let me know.

Dodder Vine (Cuscuta Sp.) is a parasitic plant that doesn't make its own food like most other plants. It steals all its food from other plants through suckers that grow into the other plants bark. The vine has no roots, no leaves, no chlorophyll.

Dodder is also called strangleweed, love vine, angel's hair and witches shoelaces and comprises a group of over 100 species.

Dodder seeds can lay dormant for almost ten years. Interestingly this parasitic plant has no connection with the ground. Once it starts growing it quickly looses any connection to the ground and relies totally on its host for nourishment, eventually killing it.

So how do you get rid of it?

Well, unfortunately, it isn't easy. All you can do is try to pull it from all affected parts of the host plants. Take care to get every fragment of it off your plants, then burn the dodder-infested plant remains.

If you have a really awful infestation or find it growing on plants you are willing to sacrifice, you can use a pre-emergent herbicide in the early spring or apply Round-up or Brush-b- Gone to kill both dodder and host plant.

Burning will kill the plants and seeds, but buried seeds will then germinate. Don't go off on a knee-jerk search-and-destroy mission every time you see a strand of dodder in the bushes, though.

Many dodders require very specific host plants and are therefore rare species themselves. If a dodder is in your garden or growing nearby among the weeds, then you should go after it with a vengeance.

If the dodder, however, is in a natural habitat growing on native vegetation, stop and think first. Watch it for awhile. If it seems be relying on just one or two kinds of plants and not attacking others or moving into cultivated areas, let it be!

Let me know how it goes.

Question #9:  What's Eating my Petunias?

Question:  All of my petunias (the ones in pots and the ones in hanging baskets) look like the petals are being eaten. Not just little holes, but the entire petal. What could be doing this and how can I treat them?

 Jane Kelsch, Murray, UT


ANSWER:  Hi Jane, sounds like you have two possible culprits.

1. Earwigs: I would check for earwigs. Lift up your pots and look around. If you see lots of long, thin bodied, black insects, you have earwigs. These can be controlled with earwig traps or spraying with insecticides.

2. Bud Worm: Sounds like you could have Bud Worm, also known as Tobacco Bud Worm. These chew all the buds leaving a tattered appearance.

Bud worms are easy to spot, just look around, lift up some leaves. If you see the worms or little black droppings, you can spray organic insecticide B.t. (Bacillus thuriengiensis) which will kill the Budworms.

Good luck!

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Fungi Problems?

Mushrooms usually appear during the rainy months, but they can appear throughout the year.

If you have lots of mushrooms growing after regular watering, it could mean compacted soil is not allowing water to drain properly.

Allow the area to dry out, aerate it, and apply some gypsite to help make the soil more porous.

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