2017 SunPatiens and New Guinea Impatiens Evaluation Results

This summer, the Commercial Flower Growers of Wisconsin hosted the largest display of impatiens in the Midwest here in our display gardens. 179 cultivars of SunPatiens and New Guinea Impatiens were transplanted June 1st and evaluated once a month, for three months, and rated 1-5 on foliage, blooms, pest and weather resistance, width and height and overall aesthetics. Most SunPatiens filled their space and were spectacular all summer while there was quite a range in vigor and sun tolerance among the New Guinea Impatiens. Click on the link below to see the overall results.

CFGW2017flower data

Ornamental and Vegetable Plant Trials

Thinking of expanding your garden? See how different plant varieties perform specifically in the Madison area. We evaluate flowers and vegetables on a number of criteria and make that information available to you! The data is also used to help seed companies ensure they are putting out top-notch products.

Fungal Friends or Fungal Foes III: Fungal Pathogens that Produce Sclerotia

What is a Sclerotium?

While many fungi create spores sexually or asexually that may persist and overwinter in the soil, some fungi ensure their survival further by making specialized structures such as a sclerotium. In general, a sclerotium is composed of a hardened mass of mycelium covered by a “rind”. As denoted above, a sclerotium is used a means for the fungus to survive for a long period of time during harsh environmental conditions. Its contents provide food reserves that allow the sclerotium to germinate and release spores when conditions are favorable.

Sclerotia-Creating Fungal Families Found at WMARS:

Sclerotinia sp. of the Sclerotiniaceae:

This fungal pathogen was found by one of the interns who specializes in ornamental horticulture while she was evaluating our petunia bed. Responsible for a condition called Crown Rot of Petunias, a brittle necrotic stem was the initial symptom that gave away this pathogen’s residence. When cut open, the stem revealed a couple of tiny sclerotia.

This disease starts when either a spore germinates on the foliage of the plant or hyphael strands enter the plant through its roots. At some point, during the time of the fungal infestation, the fungus produces its sclerotia (this logically is more likely to happen closer to the end of the season when survival is less guaranteed). Unless the infected tissue is removed, the sclerotia, at this point, are opportunistically positioned to germinate during the following season (or later seasons if the immediate one is non-conducive) and will either create active hyphae or give rise to apothecial fruiting bodies that release ascospores.  Because our plants were well established, the fungus failed to take down the whole petunia plant, yet for petunia victims that are young and lack lateral branches, this disease could be devastating.


Want to learn more information about the effects that Crown Rot has on petunias? Click the link below to watch a video that goes into further detail about this fungus, its life cycle, how to control it, etc.:

Petunias vs. Sclerotinia

Claviceps sp. of the Claviceptaceae:

I happened to come upon this fungus while observing plants in our Native Pollinator bed on the west end of the display garden. It was exciting to find these perfect specimens “blooming” from the panicle or head of the plant where seeds normally would be present. When diagnosed, this disease is referred to as “Ergot”. While the condition produced by this fungus should not be a worry to most home gardeners, species of claviceps are important to note because of the effect they have on cereal crops and the pathological conditions its sclerotia may have on human health if left unmonitored. When contaminated flour (usually rye) is produced from infected grains and a hazardous amount is consumed by a person, that person could take on a disease commonly known as Ergotism or St. Anthoney’s Fire. Essentially, the mycotoxins released from the sclerotia induce a halucinogenic state of madness in the victim. In addition to its psychological effects, it may induce muscular convulsions and gangrene which could lead to vasoconstrictions that ultimately could call for the amputation of digits or worse, limbs of the body. Because ergot is an agricultural disease and does not present itself as a big issue to the common horticulturalist, I will not go into much further detail about how to control it. Hopefully, this additional example of a sclerotia creating fungus has added some interesting trivia to your day!

Alas, I apologize, but I cannot resist telling you more about this pathogen! It is so fascinating! Below is a picture of sclerotia of Claviceps sp. that initially infected the ovaries of these grasses. It uses the plants vascular system to receive sugars so it can continue to develop until the sclerotium is fully mature. At this point, like the Sclerotiniaceae, the sclerotium may stay dormant for a long period of time until conditions become conducive to germination. When Claviceps sp. germinates, it produces a structure called a stroma, bearing ascospores that will continue its disease cycle.


Madeline Wimmer WMARS Intern

Insect of the Week

This week we’ll be talking about one of this author’s favorite pests of the gardens, the Tomato Hornworm (Manduca quinquemaculata). The image below shows a particularly large specimen that showed up in our gardens this week.

IMG_0411Named “Hornworm” for the horn-shaped feature on its posterior, the Tomato Hornworm appears in most gardens in mid to late summer, feeding voraciously on tomato foliage. As the size of the worm suggests, a single Tomato Hornworm is capable of consuming a sizable amount of foliage in its larval stage – up to four times its own body weight in a single day!

Adult Hornworms emerge after overwintering as pupae around late June. The adults mate and lay pale green, sphere-shaped eggs singly on the undersides of tomato foliage. After hatching, larvae feed and grow in size constantly for around a month. At this point the larvae, having reached full size, will drop from the plant and pupate in the soil. This pupae then serves as the overwintering phase of the lifecycle, emerging as an adult the following year. For this reason, there is only one  generation per year for this species.

Understandably, you might believe that the Tomato Hornworm is a serious threat to your garden based on its size – this however, is not often true. Because of their size, Hornworms are easily noticed and pulled off of plants by hand. They are also controlled very effectively by natural predators, particularly parasitic wasps. Depending on the species of parasitoid wasp, either eggs or larvae are attacked. This predation effectively keeps the populations of Hornworms in check in most situations. For this reason, the Tomato Hornworm is not typically viewed as an economical threat by most growers. To control this pest, simply scout your tomatoes regularly and remove any you may discover.

If you don’t feel like killing the ones you find, Hornworms make excellent short-term pets or science projects for children or interested adults! Simply place your captured Hornworm in a nice large glass jar with some holes in the lid and a few tomato leaves. Your kids (or you, if you love insects) will love the speed at which these beautiful caterpillars eat and grow in size. It’s a great learning opportunity, and a nice alternative for everyone (including the Hornworm).

If you feel like reading more about Tomato Hornworms, here’s a hyperlink for the UW-Madison Extension page on them! Happy reading: http://hort.uwex.edu/articles/hornworms

As always, thanks for reading! Until next week, happy Hornworm hunting!

-Dave Schreiner, WMARS Intern