Tomatoes and High Temperatures

Donald Buma, Norfolk Botanical Garden Executive Director

The color of your tomatoes can be affected by high temperatures.  Red pigments don’t form properly when temperatures rise above 95 degrees F.  The orange and yellow pigments are not similarly affected.  The result is often orange-colored tomatoes rather than the usual “tomato red”.  There is no reduction in the edibility or taste of the orange tomatoes.  Since tomatoes will ripen fully even though they have been removed from the vine once they begin to show color at their base, you can have nice red tomatoes despite high temperatures if you pick them when they begin to show color and let then fully ripen in the house.  

High temperatures also affect the number of tomatoes that are produced.  This is because temperatures that remain above 75 degrees F at night and day temperatures above 95 degrees F generally cause poor fruit set on tomatoes.  It is believed that the high temperatures interfere with pollen viability resulting in a lack of pollination.  Once cooler temperatures return flowers will continue to set fruit.

7/28/2010

Tomato Cracking

Donald Buma, Norfolk Botanical Garden Executive Director

Tomatoes cracking, which usually occurs on the upper part of the tomato can be either concentric (in concentric circles around the stem) or radial (radiating from the stem).  The problem is often caused by pressure inside the fruit that is more than the skin can handle.  Although a definitive reason for cracking is not known, one of the most common reasons is related to the tomato root system.  Tomato roots are generally very dense and fibrous and quite efficient in picking up water. A problem is that the root system can get out of balance with the top of the plant. Early in the season it may be small in relation to the top growth.  This can result in blossom-end rot during hot dry weather. As the season progresses, the root system may become so large and efficient that it provides too much water, particularly after a heavy rain or too much watering. The resulting large uptake of water is often the reason for the cracking tomato.  To help eliminate cracking it is important to provide even, consistent watering.  You can also use mulch which will moderate soil moisture levels. However, even if you do everything “by the book” there can still be issues with tomato cracking in some years.  There is a great variation between tomato varieties as to their propensity to crack.  Jet Star is an older variety which over the years has proven to be one of  the most crack resistant. 

7/22/2010

Slime Mold

Donald Buma, Norfolk Botanical Garden Executive Director

Slime molds are primitive organisms that often occur on mulch.  They often attract attention because of their bright colors and disgusting appearance. Common names are generally quite descriptive. For example, the "dog vomit" slime mold is a bright, whitish color that resembles its namesake. It eventually turns brown and then into a hard, white mass. There is also the "scrambled egg" slime mold, "the yellow blob" slime mold and the "regurgitated cat breakfast" slime mold. Slime molds do not hurt anything, but most people do not find them attractive and want to get rid of them. Simply use a shovel to discard the offensive organism and then stir up the mulch for aeration.

7/8/2010

Corn Earworms

Donald Buma, Norfolk Botanical Garden Executive Director

Have you ever purchased or grown corn-on-the-cob that had a large caterpillar at the top of the ear as you pulled back the husk in preparation for cooking?  This is a corn earworm and is the larval stage of the earworm moth which lays eggs on developing corn silks during the night. When the egg hatches, the larva crawls down the silk and into the ear to begin eating.  You are not likely to find more than one earworm per ear of corn because the caterpillars are cannibalistic as well as connoisseurs of sweet corn.  Control for both the homeowner and commercial grower can be challenging as silks continue to grow over a period of time. This means that even if silks are treated with a pesticide, new silk will appear that hasn’t been protected. This often requires applications every 2 to 3 days for effective control in mid June to early July when peak flights of these moths usually appear.  The only good news is that the moths do not care for silks that have dried.  And, since they begin to dry after two weeks, control treatments are only required during the first two of the three week silking-to-harvest period.  

6/25/2010

Summer Vacation For Houseplants

Donald Buma, Norfolk Botanical Garden Executive Director

Have you ever considered giving your houseplants a “summer vacation”?  It can be quite beneficial for many houseplants to be set outside for the summer.  This enables them to recover from the low light levels and often hot, dry air that they experienced during the winter months.

Once the night temperatures stay consistently above 55 degrees F, it is safe to place them outside. Select a location that has light or dappled shade and is protected from the wind.  The closer they are to an outside faucet the easier they will be to maintain also.  A deck, porch or a location that receives shade from trees or buildings is very suitable.

Do not put them in full sun.  This will cause the leaves to “sunburn” because they have become accustomed to low light conditions inside. If you are putting them out in the yard you might also want to consider sinking the pots into the ground.  This will help moderate root temperatures and also reduce the frequency that you will need to water.  

Houseplants placed outside often flourish beyond expectations.  And, the small plant you set out in the Spring often grows well beyond what it was accustomed to, and size-suited for, in the bedroom or living room when you bring it in come Fall.

5/18/2010

Spring Bulb Care

Donald Buma, Norfolk Botanical Garden Executive Director

Spring flowering bulbs are one of the true joys of this time of year.  In order to keep them as healthy as possible here is a simple three-step procedure for proper care.

• Remove the spent flowers so that the plant’s resources will go into bulb growth and energy for bloom next year rather than into producing seed.


• Allow the foliage to mature and die naturally.  The green foliage will continue the process of photosynthesis and manufacture food that will be stored in the bulb for bloom next year.  Also, avoid the occasionally seen practice of tying the foliage in a knot to make it look “neater”.  This reduces the amount of leaf surface that can absorb sunlight.


• Fertilize at the appropriate time.  Bulb roots shut down shortly after flowering and fertilizer applied once they are in bloom is essentially wasted.  The best times to fertilize are in the fall at the time of bulb planting and again in the early spring when the new growth is just beginning to emerge from the ground.

4/1/2010

Fungus Gnats

Donald Buma, Norfolk Botanical Garden Executive Director

Do your house plants have little mosquito-like insects occasionally, or regularly, flying around them?  If you experience these little plant pests, your potted plants most likely have fungus gnats.  Fungus gnats are small insects (1/8 to 1/10 inch long) that are common in high-organic-matter houseplant soils that are kept moist. These insects do not bother humans or pets. However, the larvae can injure plants by feeding on the roots. There are a number of symptoms of larval damage from fungus gnats which includes sudden wilting, loss of vigor, poor growth or yellowing of leaves.  The best means of preventing fungus gnat problems is to avoid overwatering. Existing infestations can be controlled with Bacillus thuringiensis v. israelensis, which is found in the product Knock-Out Gnats. Beneficial nematodes can also be utilized to control the fungus gnat.  Kansas State University reports that the species Steinemema feltiae is especially effective.

For a series of web pictures, various chemical controls and further links click here

3/2/2010

Spring Bulbs

Theresa Augustin, Curator of Natural Areas

You may notice that this spring is just a bit more colorful around the Garden.   This past fall and winter, the horticulture staff was busy planting over 51,000 bulbs of every type throughout the Garden. Look for hyacinths, daffodils, tulips, and crocus. The project included a massive planting of 14,000 daffodils bulbs of various types at NATO Vista across from the Tropical Garden entrance. The project was completed in record time.  Special thanks to our volunteers, the grounds staff and Jen and JoHanna from the education department for their help.  Be sure to check out the view from the Rose Garden Bridge – what a show stopper!  

2/8/2010

Companion Planting

Donald Buma, Norfolk Botanical Garden Executive Director

Have you ever wondered if companion planting really works?  In case you are unfamiliar with the concept, companion planting is a procedure that consists of planting two types of plants close to one another with the belief that it can naturally reduce pest problems.  One example is planting catnip with cabbage to reduce worm damage on the cabbage. University professors wondered also, and there are now controlled studies that have been conducted that provide “scientific” answers to this question.

The University of California looked at the effect of combining cabbage with several supposedly pest-reducing plantings that included catnip, nasturtium, marigold, summer savory and basil. The results were that the cabbage-catnip plots did have reduced cabbageworm eggs and larvae, but the amount of worm injury was the same. None of the other cabbage/companion plantings showed positive results either.

The University of Georgia has also conducted similar studies.  They grew companion plantings of beans-marigolds, cucumber-nasturtium, cabbage-thyme, eggplant- catnip, tomato-marigold, and tomato-basil. In these tests also, none of these combinations prevented insect damage from the major garden insect pests.

Despite these rather disappointing results from an “Old Farmers Almanac” standpoint, there has been some research that has shown that marigolds can be effective in controlling nematode populations.

Dutch researchers did cover crop studies looking at the effectiveness of over 800 varieties of marigolds on nematode populations.  The scientists found that apparently nematodes are attracted to marigold roots but are killed when they try to feed due to the release of ozone from the damaged root. There are two caveats.  One is that the effectiveness of killing nematodes is only with living marigold roots, once the marigolds have been tilled in, there is no further benefit.  The second is that these were not companion plantings because two crops were not interplanted.

The conclusion of these Dutch studies is that when an entire area has been covered with marigolds, cover crops reduced the numbers of the very common root-lesion nematode (Pratylenchus penetrans) enough in one growing season that other crops susceptible to that pest could be grown for two or three years without suffering from nematode damage. The French Marigold (Tagetes patula) was the most effective, with the variety 'Single Gold' providing the greatest benefit with almost 99 percent control.

1/28/2010

Planning for the Spring

Donald Buma, Norfolk Botanical Garden Executive Director

Despite ice on the bird bath and the ongoing cold temperatures, spring is on the way.  You should be receiving the spring catalogues in your mailbox soon, if you have not already, and dreams of the “perfect” garden may already have you completely forgetting about any less than bumper crops and fully floriferous flower gardens last year.  As you plan your garden, be sure to consider the All-America Selections.  They are great plants and have proven themselves very adaptable throughout the country. Pictures of two of this year’s winners and a web site for additional information are below.

Echinacea purpurea 'PowWow Wild Berry' - photo courtesy of AAS

See All the 2010 AAS Winners

Zinnia 'Double Zahara Fire' - photo courtesy AAS

Winterizing Power Equipment

Donald Buma, Norfolk Botanical Garden Executive Director

Late fall and winter weather brings the end of using most gasoline powered garden equipment.  Mowers, tillers and garden tractors should have their engines winterized if you plan to store them unused until next spring. Winterizing is a fairly straightforward process.  First, run the equipment out of gas or treat the existing gas with a stabilizer.  This is especially important given the widespread use of fuels containing ethanol.  If you do use a stabilizer, be sure to run the engine long enough for untreated gas in the carburetor bowl to be burned and replaced. I also like to remove the spark plug, replace if worn, and give a shot or two of sprayable oil into the hole where the spark plug came out. Then, with the spark plug still removed, give the starter rope a pull or two to spread the oil throughout the cylinder. Since the engine is warm because you have been running it, this is also a good time to change the oil.  Be sure to also check the air filter and clean or replace it as necessary. It is surprising how often small engines fail to run properly because of a dirty air filter.  A little extra care in the fall can ensure a better running mower or tiller next season.

12/3/09

Cicada Killers

Donald Buma, Norfolk Botanical Garden Executive Director

Have you seen any flying insects lately that look like giant yellow jackets?  If you have, they are most likely the eastern cicada killer, Sphecius speciosus.  Actually it is considered a beneficial insect because it helps to regulate cicada populations. This wasp gets its common name from the fact that it hunts cicadas, which becomes the food source for young cicada killers.

Cicada killers are solitary wasps, with the female digging a 6 to 10-inch burrow (½ inch in diameter) in the ground. These diggings are usually seen in sandy or loose soil. A pile of soil or sand, depending on the soil type, typically surrounds the entrance. The female locates and stings a large insect such as a cicada or katydid and paralyzes it.  She then brings the insect back to the burrow. This can be quite an operation because the size of the cicada.  The cicada killer generally launches from a branch holding on tightly to the cicada and essentially does a powered glide towards its burrow.  It may have to drag it the final distance to her burrow.  Once in the burrow she places her prey into a chamber and lays an egg on the surface of the paralyzed insect.  The female cicada killer eventually covers the burrow, digs another, and repeats the process. The egg hatches into a grub-like, legless larva that consumes the paralyzed insect. Full-grown larvae overwinter in the burrow, pupate in the spring, and emerge as an adult during the summer—usually July and August.

Cicada killers can be up to 2 inches long and black to red in color, with yellow-banded markings on the abdomen. The head and transparent wings are reddish brown. They are not dangerous, but they are intimidating.  Male cicada killers establish territories and patrol for intruders. A male cicada killer wards off other males that enter his territory.  Anyone else, such as a human, walking into the territory is typically confronted by a very large wasp, which hovers in front of the face and zips to the side and back. However, after determining that the intruder is not a rival, the male cicada killer ignores the individual. Cicada killers are unlikely to sting a person. Wasp and bee stingers are modified egg-laying devices (ovipositors), so males are unable to sting.Females may sting if crushed, either by being stepped on with bare feet or grabbed with bare hands.

Cicada killers are more common in areas with bare soil.  Areas that are mulched, covered with grass or ground covers are much less likely to harbor cicada killers.  Sandboxes should be covered with a tarp when not in use and sand below swings, jungle gyms, or other playground equipment should be replaced with bark mulch or shredded tires.

They are fascinating insects and if you have the opportunity to carefully observe one it may well be worth the time to interrupt your busy day-to-day activities and watch nature in action.

8/3/09

Leaf-Spot Diseases on Tomato

Donald Buma, Norfolk Botanical Garden Executive Director

Septoria leaf spot and early blight are two leaf-spot deases on tomatoes that start showing up about this time of year.  Both of these diseases are characterized by brown spots on the leaves.

Despite their names, Septoria leaf spot usually appears earlier in the season than early blight. Septoria produces small dark spots whereas the spots made by early blight are much larger and often have a distorted “target” pattern of concentric circles. Heavily infected leaves will eventually turn yellow and drop. Younger leaves are less susceptible than older leaves.  As a result you will see the disease generally start at the bottom of the plant and work upward.

Prevention measures to limit these diseases are fairly simple and consist of using mulch and stakes or cages to help keep plants off the ground. Staked or caged tomatoes have better air circulation around the plants which allows foliage to dry quicker.  A good layer of mulch helps to prevent water from splashing and carrying disease spores to plant leaves.

However, sometimes even if you use the best cultural practices and exercise diligent prevention measures, these diseases will still develop. If that is the case it may be necessary to utilize a fungicidal control.  Check with your local extension agent, garden center or nurseryman for the most appropriate control recommendations.

6/25/09

Carpenter Bees

Donald Buma, Norfolk Botanical Garden Executive Director

Carpenter bees may very well be swarming around outside your homes about now.  They resemble bumble bees but have bare abdomens that are a shiny black to iridescent green. In the spring these bees, which overwinter as adults, are emerging and looking for mates. The male bees can be rather aggressive and may “dive bomb” people in their vicinity.   However, they are harmless as they can not sting. The females are capable of stinging but generally will not do so unless handled or molested.  

After mating in the spring, female carpenter bees tunnel into wood to lay their eggs.  They can be quite destructive as they produce round holes about ½ inch wide. The eggs develop throughout the summer and the young adults will spend the winter in these tunnels. The next spring the cycle begins again. The next generation of carpenter bees may use tunnels that are already there, they may enlarge or extend the current tunnels, or they may excavate new ones.  

Carpenter bees prefer to attack wood that is bare, weathered, and unpainted. They prefer softwoods such as redwood, cedar, cypress and pine. Common nesting sites are eaves, window trim, siding, decks, and arbors and trellises. The best way to avoid an infestation is to keep all exposed wood surfaces painted. Stains and varnishes will repel the bees to some degree but are not as effective as paint. Once an infestation has been detected, the tunnel entrances can be treated with an insecticide that has residual activity. Treating at night is most effective while the bees are inactive in the tunnels. The holes should be left open for a few days to allow the bees to come in contact with the insecticide and distribute it throughout the tunnels. Then, the holes can be plugged to prevent further use by carpenter bees and reduce the chances of wood decay.

5/26/09

A Better Tasting Tomato

Donald Buma, Norfolk Botanical Garden Executive Director

We can all agree that some tomatoes certainly taste better than others.  Science has now apparently determined why – a compound known as furaneol.  Not only has this compound been identified, it is in higher concentrations in tomatoes that taste better – particularly heirloom varieties, but the gene that controls the level of furaneol has also been identified and has been incorporated into breeding programs.

There are a number of varieties that have been recently introduced or just coming onto the market.  Look for them at your local garden center or nursery.  They are also available from several mail order catalogues.  Sources and names of the of the flavor-enhanced varieties include the following.  Harris Seeds has Mountain Glory, Red Defender, SecuriTY 28 and Scarlet Red. Stokes Seed  carries Scarlet Red and Mountain Glory. Park Seed has ‘Fabulous’.  In addition to the flavor-enhancing gene, these varieties are also reported to have high disease resistance, compact growth and produce a large number of tomatoes.  Give some of them a try this year and see if, in fact, they do have a better taste.

A web site that has just about all the information, and them some, that you might ever want to know about tomatoes is On-Line Tomato Vine.  This site is provided by Keith Mueller a graduate of Kansas State University who is working on breeding disease resistance into heirloom tomatoes.