Jim Shields' Garden Notes
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Blog Home : May 2007

- Suddenly it's Summer

Spring ended a month ago in a crush of winter weather. All the spring flowers, especially the magnolia blossoms, disappeared almost overnight. Since then, we have slowly been working our way back to seasonable weather, but we seem to have overshot. It's more like summer this week.

Weeds and Bugs

Weeds are my surest sign of summer, and they are everywhere now. We are starting to get our helpers back on the job, and weeds are the first and most obvious target. Many areas will have to be hand weeded, but on at least some of them, we can spray herbicides to cut out some of the manual work.

Many of the monocot plantings (daylilies, iris, spring bulbs) will tolerate Lontrel® plus Fusilade®. We may be too late for the Fusilade to stop the grasses, but the Lontrel should work fine all summer long on the broadleaf weeds.

The most persistent weeds are dandelions and Canada Thistle. Roundup® does not seem to do permanent harm to either of these fiends. Hand weeding is almost useless, as they come right back from the roots unless you excavate the entire area down about 18 inches deep.

Weeds make me appreciate the greenhouses even more!

On the other hand, in the greenhouse, the mealy bugs are appearing again. Yesterday, I sprayed part of the big greenhouse with AVID®, which is a very expensive, very active miticide that is also very good against mealy bugs. It has a systemic effect, and we will only have to spray with it every 4 to 6 weeks to keep the spider mites down. We may have to come in and spray with a different insecticide in 3 to 4 weeks to get all of the mealy bugs.

The follow-up sprayings may be Talon® or Merit® wettable powders. Last August, I used all three of these insecticides in succession to knock down the mealy bugs, after letting them get away from me earlier in the season. I sprayed every three weeks over a 6 to 7 week period, using a different psray each time. That really knocked the mealy bugs down, and they stayed down for at least 6 months.

If you are going to use pesticides in your garden or greenhouse, read the label and the directions carefully. Wear gloves, goggles, and whatever else you may need to keep the chemicals and the spray solutions off your skin. Put your clothes in the laundy as soon as you finish spraying for the day; then take a good shower. I worked 40 years as a bench chemist in the lab, and I respect these chemicals. You should too; be careful!

Good gardening,


- Pests and Pesticides

Summer is here, gardening is getting to be pusy, and there is less time to sit and think. My comments are likely to come at longer intervals for awhile. I trust you are also preoccupied with the practice of gardening, too. We can all sit and think again next winter.

Recently, there was a discussion of Arisaema Rust (Uromyces ari-triphylli) in the Alpine-L list. This reminded me of Susan Bergeron's excellent web site devoted to Daylily Rust (Puccinia hemerocallidis).

Another place to look for discussions of Arisaema Rust is in the archives of the Arisaema-L list.

Rusts and their relatives are apparently strange things -- even stranger than we might have imagined. Larry Wallace, of Cincinnati, Ohio, pointed out in the same Alpine-L thread that the rusts, Phytophthora (root rot), and other things have recently been moved from their former Kingdoms (e.g., Fungi) to a group of protists, now in Kingdom Stramenopila. Links provided by Larry include http://botit.botany.wisc.edu/toms_fungi/m2001alt.html and http://courses.bio.psu.edu/fall2005/biol110/tutorials/tutorial30.htm . Thnaks very much, Larry!

As mentioned here last week, I've resumed the battle against mealy bugs. I'm not sure what the various labels say, but in the past I've used sprays of Talus® (buprofezin), of Avid® (abamectin), and of Merit® (imidacloprid) as well as Marathon® granular imidacloprid in the potting soil. One of these, or perhaps the sequential treatments with all of them, does a pretty decent job of knocking the population of mealy bugs down to almost (but not quite) zero.

Avid® has the extra benefit that it is labeled for and quite effective against many kinds of spider mites as well.

Talus® is a growth regulator. The three mentioned above, buprofezin, abamectin, and imidacloprid, comprise three distinctly different chemical classes of insecticides. Their use in rotation ought to greatly delay the emergence of pesticide resistance in the pests being treated. At least I sure hope so!

A Windowsill Crinum

One a different note, a bulb of Crinum minimum that I have been growing in the greenhouse in a 1-gallon pot has bloomed. The bloom was a single floret, of quite normal size for any Crinum flower. It lasted only a single day -- I failed to get any pollen on it, let alone save any of its pollen. I had hoped to eventually generate some hybrids between C. minimum and C. acaule. Oh, well......

Comments on Clivia Seeds

span class="entrytext"> We have noticed that many crosses of Clivia with bitone or multi-tone flowers give us seeds that fail to germinate. We have crossed plants in the Solomone "Watercolor Washed" series with each other and seen this lack of germination, as well as in crosses between Conway <"Particolor" plants with each other and crosses between "Watercolor Washed" plants and "Particolor" plants.

This leads me to believe that the two lines may have many genes in common. Certainly, Dave Conway Sr. and Joe Solomone used to swap plants pretty regularly, it seems.

Good gardening,






- Calla Lilies

Calla lilies, actually Zantedeschia vareties, are generally not hardy here planted outdoors. The exception seems to be when they are planted outdoors close to the walls of my greenhouse. I have a large clump of Zantedeschia 'Green Goddess' planted right against the foundation at the south end of the greenhouse, and a small clump of the dark red-brown 'Black Pearl' planted on its east side. Both have come back year after year.

There are more interesting plants that we keep in pots and carry over winter in the greenhouses. If we water them a bit in spring, they quickly start to flower in the greenhouse. Right now, the wild species Z. pentlandii is blooming with a large yellow calyx. One seems to be about 4 inches across the open end.

Zantedeschia pentlandii, native to the Belfast district of Mpumalanga Province in South Africa. It grows in rocky places along mountain streams.

Zantedeschia pentlandii is now available from several mail order bulb companies. However, I bought mine from Charles Craib in South Africa a few years ago, when no one else offered them anywhere. I think I got tubers at most ½inch in diameter. The leaves are solid green, and the flowers are quite striking when in bloom.

The white flowered Z. albomaculata has the same narrow, arrowhead shaped leaves as Z. pentlandii, but with white or translucent spots in them. It is another native from South Africa. This one is common in cultivation, and I have some I grew from seeds and others that I received as pass-along gifts from friends.

Another species is Z. rehmannii, which is probably the most cold-resistant species. It grows at very high altitiudes in South Africa. It has solid green leaves with an elongated, very narrow arrowhead leaf form. The flowers, whose narrow calyx is pink colored, are smaller than the other species. I suspect that this species is the ultimate ancestor of the red, pink, lavender, and "black" flowered Calla lily hybrids of commerce.

Irma likes black flowers, so we have two varieties of dark Calla lilies here: 'Black Forest', which we think is an American trade name for the European 'Schwarzwalder', and also 'Black Pearl'. We have not tried to cross pollinate these two varieties, since one of them blooms early in the summer and the other blooms late in summer. Both are attractive "black" Calla lilies, both have white spotted leaves, and between them they provide us with black blooms through most of the summer. A large tub full of these makes a very nice deck or patio specimen when in bloom.

The large white Calla lily, Zantedeschia aethiopica, is evergreen. 'Green Goddess' is a variety or sport of Z. aethiopica. I'm amazed 'Green Goddess' survives outside our greenhouse, since the cold weather kills it to the ground every winter.

Most of our Z. aethiopica are grown in 2-gal. to 5-gal. pots and are kept in the greenhouse over winter, with occasional watering. They tend to start blooming in January to March. They will rebloom sporadically during the summer, if we keep them well watered. I often grow these under dappled shade (in the lath house), while the others are kept in full summer sun.

One strain of Z. aethiopica we have has blooms with a light pink tint to the calyx. This is quite nice.

Good gardening,


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