What’s All the Buzz About?

by OCMGA Master Gardener Tammy Borden

The water streamed out the end of the hose I held to water the impatiens beneath my birch tree. It was then I heard the familiar buzz of a hummingbird zoom by. Despite being among the most fascinating birds of summer, as the days roll by their presence is more familiar and I become accustomed to their antics. But something was different this time. Though it hovered and darted from blossom to blossom with the same agility and precision as a hummingbird, the flying creature was slightly smaller than usual. It was then I realized it was no bird at all, but a moth earning a similar nickname, the hummingbird moth. It’s more common name is a White-lined Sphinx Moth (Hyles lineata).

I dropped the hose and ran to get my camera. When thinking of moths, many may envision images of drab, brown winged creatures most commonly seen hovering around illuminated porch lights. The Sphinx Moth, however, is a colorful insect with nearly a 4” wingspan which is most often seen in early evening sipping nectar with a long proboscis from a wide range of flowers, much like hummingbirds. In my garden, they seem to enjoy zinnias, petunias, salvia, coral bells and impatiens.

If you’d like to attract this beauty to your yard, consider adding some of the host plants for the caterpillars, including apple, evening primrose, elm, grape, tomato, purslane, four o’clock and Fuschia. The caterpillars in our area are generally a bright green with spots lining its body and a small horn, resembling a tomato hornworm. While they seem like an exotic species, they are really quite common throughout the United States and southern Canada. They also occur in South and Central America north through Mexico and the West Indies as well as Eurasia and Africa.

Keep a watchful eye on your garden this summer, especially when that familiar hummingbird flies by. It may not be a bird at all. Instead, you might just be witnessing one of these fascinating moths.

 

UW-Extension Tips

We’re based in Wisconsin and can’t say enough good things about the expert help that is available to us through the University of Wisconsin – Extension. In a recent email to all Master Gardener members, there were two really good articles and I’m reproducing them here.

Expert’s Tip: 10 Tips for A Successful Tomato Container Garden

Ann Wied, Waukesha County UW-Extension Consumer Horticulture Educator

Not enough time or space for a garden?  Tomatoes grow great in containers. Here are a few tips to use yourself or share with others …

1. Choose a compact, bush, or dwarf tomato variety. These tomatoes are often labeled at garden centers as “great for a container gardening”.
2. Buy healthy, resistant varieties.  Choose varieties that are resistant to diseases prevalent to where you live.  Look for this information on the plant tag or garden catalog.
3. Choose a container large enough to provide support for your tomato.
4. Don’t rush to plant your tomato. Plant near the recommended planting date for your area. Even if you can protect the plants from frost and/or cold night air, cool temperatures can keep growth slow, cause nutrient deficiencies, and prevent fruit set. In addition, once fruits start to form, cold temperatures can cause the tomatoes to become deformed.
5. Place the container in an area that has at least 4 hours of direct sunlight each day.
6. Water your tomato plant whenever the top 2 to 3 inches of soil is dry. This may be every day or every other day if the weather is hot and dry.
7. When you water, water until it drains through the bottom of the pot and don’t let the plant sit in excess water.
8. Fertilize once a month throughout the growing season with a fertilizer labeled for vegetable plants.
9. If the tomato gets too large or bushy, support it with a small cage or stake and/or prune out some branches.
10. Monitor for disease and insect problems. If a disease occurs, remove and destroy infected leaves or the entire plant if the disease is severe.

 

Click here for a version (pdf) you can print and hand out to clients!

Expert’s Tip #2: Tips on preventing seed production when hand-pulling garlic mustard plants

Mark Renz; Associate Professor and Extension Specialist; University of Wisconsin-Madison

Ever wondered about these questions:

 

• Is there a developmental stage where garlic mustard plants can create viable seed if pulled?

• How does different disposal methods impact seed production?

 

I have summarized the results of research done on this topic (read the reference for all the details and their specific conclusions):

What stages can garlic mustard produce viable seeds when hand-pulled?

Plants were hand-pulled over three consecutive week sand separated into three phenological groups:

1. flowering: < 5% of flowers developing into fruit
2. early-fruiting: 40%-60%of flowers developing into fruit
3. late-fruiting: > 95% flowers developing into fruit

Of these stages only the flowering stage didn’t produce any viable seed or seedlings the following year. While lots of variability existed with the later two stages, each of these produced viable seeds. Although this experiment was conducted atone site in one year other studies using phenology have found consistent results from year to year and site to site. Thus this is clear evidence to me that the flowering stage is a safe timing to not worry about seed production if plants are hand-pulled.

What is the best method to dispose of hand-pulled garlic mustard plants?

Three disposal treatments were evaluated where plants were left in field conditions for three weeks:

1. left in a pile on the ground
2. scattered on the ground
3. hung over tree limbs

Results found that regardless of disposal method, similar viable seed and seedlings the following year were found. While these results are encouraging, they were conducted over one year in one location in Ohio. I would caution about over-interpreting this information as different environmental/physical conditions may alter the result.

Can second-year garlic mustard plants resprout from taproots if just shoots are removed?

Plants were cut at the soil surface at one of four phenological stages:

1. budding: no flowers
2. flowering: < 5% of flowers developing into fruit
3. early-fruiting: 40%-60%of flowers developing into fruit
4. late-fruiting: > 95% flowers developing into fruit

While some plant stages resprouted quickly from the first three timings (bud, flowering and early fruiting) no resprouting occurred with the late late-fruiting timing. Regardless of timing, all treatments did not result in the production of viable seed and plants did not survive the following year. Thus stage of shoot removal doesn’t appear to be that important, and while resprouting can occur it may not produce any viable seed. Similar to above I would caution about over-interpreting this information as lack of shoot resprouting could have been the result of site specific factors.

The big picture:

In summary, this research confirms that viable seed production can occur if hand-pulled after the flowering stage. If you are hand-pulling after this timeframe it is recommended to plan on some of the seeds being viable. Realize that while zero seed production is the goal, all treatments had large reductions in the production of viable seed (largest # of viable seeds per plant was < 20).

Consideration of the level of infestation should be included in the decision making process as well as this information. If hand-pulling plants in an area recently infested with few plants and limited to no garlic mustard seed bank I would recommend not taking any chances and bagging/removing plants if past the flowering stage. However, if the location has been infested for multiple years, a seed bank is likely present and I would be more willing to leave plants after flowering on site. A few additional viable seed won’t be the end of the world as repeated trips for multiple years will be needed regardless of the success in any one particular year.   

Reference:

Chapman, JI, Cantino PD and McCarthy BC. 2012. Seed Production in Garlic Mustard (Alliaria petiolata) Prevented by Some Methods of Manual Removal. Natural Areas Journal Jul 2012 :Vol. 32, Issue 3, pg(s) 305-315.

Flowering and Fruiting Issues in Solanaceous and Cucurbit Crops

by Lisa Johnson, horticulture educator for Dane County UW-Extension

Often, this time of year, I get calls from gardeners asking why some vegetables are not fruiting. Unpredictable spring and summer weather temperatures can adversely affect crops, especially tomato, pepper, and eggplant in the Solanaceae family, and winter squash, cucumbers, pumpkins, melons, and summer squash in the Cucurbitaceae family. These plants rely on a certain range of temperatures to initiate flowers, bring them to maturity, and produce fruit. Fruit production can be affected any time during this process.

Temperatures at night have the greatest impact. If temperatures are too hot or too cold for even a few days during flowering, plants may abort flowers or fruits. For solanaceous plants, daytime temperatures above 85 F for several days, nighttime temperatures above 70 F, or nighttime temperatures below 55 F cause fruit to abort. If you think back to 2012, which had high daytime and nighttime temperatures, low fruit production is understandable. In fact, temperatures over 104 F for four hours can cause tomato flowers to abort.

Temperatures and Pollination

Tomatoes, peppers, and eggplants are self-pollinating, but cucurbit flowers must receive multiple pollinator visits for complete pollination to occur. Squash, for example, requires an average of 12 visits by a pollinator to set fruit. And it has to happen fast. Pumpkin and squash flowers open at temperatures above 50 F; cucumber and watermelon, above 60 F; and muskmelon above 65 F. But these flowers only stay open and viable for a day in the case of watermelons, muskmelons, and cucumbers, and half a day or less for other cucurbits.

Also, all cucurbits are not alike. Some plants have separate male and female flowers, or female flowers only, or have perfect flowers, with male and female parts in the same flower. If they have separate male and female flowers, usually male flowers open first. Early in the season, more male flowers are open than female flowers, but you need both to produce fruit! As the plant ages, the proportion of female flowers increases. Cucurbits are affected by other factors that influence whether a flower will be male or female. Cool temperatures promote female flowers in cucumber, squash, and pumpkin. Conversely, high temperatures promote male flowers and delay female flower development. In pumpkins, temperatures of 90 F during the day and 70 F at night lead to abortion of female flower buds.

Light levels also affect flower development in cucurbits. High light levels promote female flowers; shade can reduce those numbers. The bottom line is that a lot can happen between flowering and fruiting!

Designing Tall

Want some color and height at the back of your flower garden, but not interested in shrubs? There are many tall flowers that can anchor the back of a border. Which ones you choose will depend on the space available (some of them are as wide as they are tall) and on your growing conditions.

Foxgloves, for instance, will grow to 6 feet if they’re in moist, nearly neutral soil in semi-shade, but they might top out a bit below 4 feet if they’re in average soil in the sun. The same goes for black snakeroot (Cimicifuga racemosa), which might stretch to 7 feet or more if happy and dwindle utterly if not.

Foxgloves are usually columnar, their tall flower spikes rising almost leafless from a broad rosette at the bottom. Snakeroot is rangier; sending out beautifully cut-edged leaves almost all the way up the stem. Meadow rue (Thalictrum spp.) also sends out leaves all the way up, but they, like the flowers, are lacy and delicate, so the overall effect is light. T. rochebrunianum, which has purple blooms, and T. speciosissimum, (aka T. flavum ssp. glaucum), which has pale yellow flowers and bluish leaves, are both 4 to 6 feet tall. White-flowered T. polygamum can grow to 8 feet.

Joe Pye weed (tall and purple) in my garden

Other tall flowers include delphinium, Caroline lupine (Thermopsis caroliniana), plume poppy (Macleaya cordata), Ligularia spp., Japanese meadowsweet (Filipendula purpurea), foxtail lily (Eremurus stenophyllus), Joe Pye weed (Eupatorium purpureum), and globe thistle (Echinops bannaticus). Read cultural descriptions carefully before you buy; many of these plants have very specific needs and some — especially plume poppy and Joe Pye weed — are very aggressive spreaders.

July Already?!

Seems like summer has barely started and we’re already looking ahead to July — the height of summer. Days are long, temperatures are most likely at their highest and may even exceed 100ºF for days at a time in the South, Southwest, and Midwest. If all goes well, you’re harvesting something delicious from your garden almost every day, and this is also the peak time for picking herbs. But, like June, July is often a dry month, too. Watering is crucial. Most crops need a steady, unbroken supply of water. Interruptions cause problems such as flowers falling, fruits failing to form, skins splitting, premature bolting, and diseases such as tomato blossom end rot. Spreading mulches helps conserve moisture from any rain you do get — and will also control weeds.

Top tasks for July

• Harvest French and runner beans, zucchinis, carrots, beets, onions, shallots, new potatoes, and summer salads.
• Pick cherries, strawberries, raspberries, currants, gooseberries, and blueberries.
• Sow salad crops and the last of your beets, Florence fennel, French beans, and peas for this year.
• Climbing beans don’t really know when to stop. Pinch out the growing tips when they reach the top of your canes or they will quickly become tangled and top-heavy.
• Plant out cabbages, cauliflowers, brussels sprouts, broccoli, and kale for the autumn and winter.
• Continue to ensure that peas, brassicas, and soft fruit are all securely netted to keep off scavenging birds.
• Pull earth up around the stalks of brussels sprouts and other brassicas if they seem unsteady, and give them a top-dressing of nitrogenous fertilizer or an organic liquid feed. Keep an eye on potatoes and if necessary continue to earth them up.
• Start regularly watering tomatoes and peppers with a liquid feeding as soon as you see that the first fruits have formed. Feeding encourages both flowers and fruits.
• Water as often as you can to keep crops growing healthily and to prevent them from bolting.
• Feed tomatoes regularly and pinch out side shoots.
• Thin out apples and pears if it looks like you’re going to have a bumper crop.

“Weed, water, mulch” should remain as much of a mantra as it was in June. All three are still high on the list of the most important tasks of the month. Regular watering, in particular, is vital for the successful growth of crops. July is the month for summer-pruning certain fruit trees and bushes as or just after they finish cropping — cherries, currants, gooseberries, and summer-fruiting raspberries.