The riots of spring are upon us, almost one hundred years this May after Igor Stravinsky, Sergei Diaghilev and Vaslav Nijinsky’s Rite of Spring ballet stunned the high cultures of music and art.
Like their sacre du printemps of dissonant sounds and colors, this week’s spring and its prelude are a mélange of icy weather and touches of sun, the honks of geese and the first songs of spring peepers, the emergence of crocus and leaves of spring beauties with the almost immediate retro of frost and bitter winds. Soon enough, sun and greater warmth shall sustain, wildflowers will cover the woodland floor and forsythias and tulips shall bloom. About time.
Artists of the horticulture bent are eager to hurry that spring and two recent talks, at a webinar for OSU Master Gardeners of OSU who answer email questions nationwide, and gardeners at the Raising Richland program of OSU Extension in Mansfield last week, provided plenty of questions, with special regard for two favorite garden plants: impatiens and tomatoes.
Q: Will there be a shortage of impatiens this spring and summer?
A: Almost certainly, yes. The toll of the downy mildew disease of bedding impatiens (Impatiens walleriana) will result in fewer of these No. 1-in-sales bedding plants being available in garden centers.
This is a big deal for gardeners who are accustomed to the rivers of vibrant color impatiens provide to the landscape. Many impatiens are started in the south and finished in northern greenhouses and because of this disease larger growers are planting less. Sanitation and fungicide use will be rigorous in these greenhouses, but this is a difficult-to-control invasive pest.
New Guinea impatiens and SunPatiens hybrids are not affected by the disease. Other shade-tolerant replacements for impatiens include wax begonias, coleus, and browallia.
Q: Will this downy mildew spread to other plants than impatiens?
A: No, the pathogen, Plasmopara obducens, only infects Impatiens walleriana, its hybrids, and certain other impatiens species, such as our native jewelweeds, Impatiens capensis and Impatiens pallida. This downy mildew pathogen is different from other downy mildews that infect rose and viburnums and cucumbers and grapes.
The pathogen survives over the winter inside on infested plant debris in soil, and potentially outside from overwintering oospores of Plasmopara obducens on diseased plant debris in gardens and at least theoretically on wild jewelweeds.
Q: Where can more be learned about downy mildew of impatiens?
A: Google the “National Floral Endowment” and “downy mildew of impatiens” and get everything from images of signs and symptoms to control recommendations to videos of the disease.
Another good source will be the OSU Extension Buckeye Yard and Garden Line (BYGL) newsletter that has archived materials from last year (the second and third items to pop up when I googled “Downy Mildew of Impatiens” last week), and that will debut for the 2013 season the first Thursday of April. Check out http://bygl.osu.edu for the latest on impatiens, trees, shrubs, lawns, fruits, flowers and vegetables, including … tomatoes.
Q: Can tomatoes receive too much water?
A: Indeed they can and do often receive not only too much, but also too little water.
In extreme cases of either the result is plant wilting and decline, from either root rot from not enough oxygen in wet soils that results in a root system not supplying enough water to the tops of the plants, or simply drought not supplying the needed water.
More commonly, alternating dry and wet periods contribute to blossom end rot on the tomato fruits. Blossom end rot is caused by a calcium deficiency in the developing fruit that is caused by the roots not providing the calcium, because of dry or wet conditions limiting water uptake. To moderate water availability for tomatoes it is best to mulch, preferably with coarse materials such as straw.
Q: Can tomato plants receive too little light?
A: Yes, resulting in tall, scraggly plants that produce too few fruits for the table. That is why you want to plant tomato gardens in full sun.
Often when tomato plants become scragglier and with fewer fruits in the same garden over the years, gardeners are puzzled. We insist we are using the same cultural practices, using the best of seeds, and that our neighbors’ tomatoes are thriving. What is this calamity? Trees, those most wondrous trees in the backyard, are ever growing, and in some cases we fail to realize that each year they shade the garden a little more, resulting in the tragedy of fewer tomatoes.
Q: Are some trees worse than others for tomatoes?
A: Other than too much shade, trees are no threat to tomatoes, unless the trees are walnuts. Our native black walnut (Juglans nigra) really does have it in for tomatoes and certain other plants.
Black walnuts produce a chemical, juglone, that is a form of botanical warfare in that it is poisonous to those plants, causing them to wilt and die. A 40-foot black walnut tree 50 feet from your tomato garden is a bad scene, in that the roots of the walnut, which grow well out past the dripline of the tree, will cause the tomato plants to wilt due to juglone exuding from the roots. Not very companionable plants.
So the riots and rites of spring begin. Let us join in the danse de la terre from Le Sacre du Printemps: Let us “break into a passionate dance, sanctifying and becoming one with the earth.”
Jim Chatfield is a horticultural educator with Ohio State University Extension. If you have questions about caring for your garden, write: Jim Chatfield, Plant Lovers’ Almanac, Ohio State University Extension, 1680 Madison Ave., Wooster, OH 44691. Send email to email@example.com or call 330-466-0270. Please include your phone number if you write.