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Yews in Connecticut
Richard S. Cowles
Conn. Agric. Expt. Station, Valley Lab.
P. O. Box 248
Windsor, CT 06095
Phone (860)683-4983
Fax (860)683-4987
Email Richard.Cowles@po.state.ct.us
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Insecticide Products used in Connecticut Yew Nurseries, 1999
a There was a total of 505 acres of yew grown. DISEASES Roots in flooded or waterlogged soils are damaged and die from oxygen deficiency. Damage can be sudden or gradual, depending upon the flooding conditions. Entire plants can die if flooded for only a few days during the growing season. Flooding can result in stress that predisposes roots to rot organisms, such as Phytophthora spp. Above-ground signs are non-specific and include a general decline and lack of vigor. Visible signs are often not evident until long after flooding and involve chlorosis or yellowing of the foliage, edema, reduced and stunted growth, twig dieback, needle drop, root death, and in extreme cases, whole plant death (CAES, 1999). One grower reported observing root rot in his yews.Controls Disease management includes practices that minimize wet soil, such as selection of an appropriate planting site, installation of subsurface drainage systems, and use of proper planting practices and cultural practices that maintain plant vigor and stimulate growth. It is also helpful to prune dead or dying tissues to minimize secondary invaders and opportunistic pests. Once a plant is infected, recovery is unlikely (CAES, 1999). Plants surrounding dead or dying individual shrubs can be protected from the spread of root rots with fungicide sprays or drenches, which must applied on a preventative basis. Among the compounds registered for use in Connecticut are metalaxyl and fosetyl-Al. Chemical control of plant diseases in yews is unimportant in Connecticut, as there were no fungicides applied (CAES, 1999).WEEDS Each field in Connecticut is likely to have a large complex of weed species present. However, certain weeds are especially important because they are present in most fields (e.g., crabgrass), or they are especially difficult to control where they do occur. Some weeds, such as grasses and Pennsylvania smartweed, are important to control because they attract Japanese beetle or elicit their egg laying (Smitley 1994).Chemical control Weed control usually starts by spraying a combination of a preemergence grass and preemergence broadleaf herbicide in the spring, before budbreak, to control summer annuals, those weeds germinating in the spring or early summer (e.g., crabgrass and ragweed). Another application of a preemergence broadleaf herbicide (Princep, Gallery, or Goal) is usually made in the fall to control winter annuals, which germinate in the fall, overwinter as rosettes, and bloom in the spring (e.g., field pansy) (Ahrens 2000). Escapes and perennials are controlled separately, either as spot treatments if the infestation is localized, or with shielded sprays if the problem is more widespread. Each chemical tool has strengths and weaknesses with respect to the spectrum of weeds controlled. Therefore, monitoring is required to determine the weed control needs in particular fields, to better match those needs with the most efficient herbicide (Ahrens 2000). Cultural control Some growers resort to frequent cultivation with sweeps, supplemented by hand hoeing. Cultivation has several disadvantages. Besides the possibility of soil compaction, mounding of soil at the base of shrubs, and high labor costs, disturbance of the soil may cause dilution of preemergence herbicides, leading to a shortened period of effectiveness during the growing season. Cultivation also brings weed seeds near the soil surface, where they may germinate readily. Cultivation thus may lead to a "treadmill" situation, in which, once started, there is a need for follow-up cultivation every 10 - 14 days thereafter. Weeds have been grouped based on their biology and the chemistries of herbicides used to achieve control. In all cases, the Weed Science Society of America common names are given (Weed Science Society of America 1989). Annual grasses, such as barnyardgrass; crabgrass; fall panicum; giant, green and yellow foxtails; and witchgrass. Available Chemical Control Fluazifop-P-butyl (Fusilade 2 E). Applied at 16 - 24 fl. oz. per acre (0.25 - 0.375 lb a.i./Ac), this is a post-emergence grass herbicide. Metolachlor (Pennant 8 E). Applied at 2 - 4 lb a.i./Ac. This material is especially important for control of nutsedge. Napropamide (Devrinol 50 DF or 4 G). Applied at 4 lb a.i./Ac. This material is especially useful for transplant beds, because it has excellent safety for plants with less-developed root systems. Oryzalin (Surflan 4 F). Applied at 2 - 4 lb a.i./Ac. Pendimethalin (Pendulum 2 G, 3.3 E, or 60 WDG). Applied at 3 - 4 lb a.i./Ac. Prodiamine (Factor 65 DF). Applied at 0.65 - 1.5 lb a.i./Ac. Sethoxydim (Vantage 1 E). Applied at 2.25 - 3.75 pt/Ac. (0.28 - 0.46 lb a.i./Ac.), this is a post-emergence grass herbicide. Annual broadleaved weeds, such as common chickweed, field pansy, horseweed, Pennsylvania smartweed, purslane, ragweed, redroot pigweed, and shepherd's-purse. Available Chemical Control Oxyfluorfen (Goal 2 E). Applied at 0.5 - 1 lb a.i./Ac. Isoxaben (Gallery 75 DF). Applied at 0.375 - 1 lb a.i./Ac. Simazine (Princep 90 DF or 4 F). Applied at 1.5 - 2.5 lb a.i./Ac. This product is greatly relied upon because of its low cost and high efficacy. Oxydiazon (Ronstar 2 G or 50W). Applied at 3 - 4 lb a.i./Ac. Perennials, such as Austrian field cress, bird vetch, Canada thistle, creeping yellow cress, dandelion, field bindweed, horsetail, milkweed, mouse-ear chickweed, mugwort, quackgrass, and yellow nutsedge. Available Chemical Control Asulam (Asulox 3.34 E). Applied at 2.5 - 3.3 lb a.i./Ac. Dichlobenil (Casoron 4G). Applied at 4 - 6 lb a.i./Ac. Pronamide (Kerb 50W). Applied at 1 - 2 lb a.i./Ac. Clopyralid (Lontrel 3L). Applied at 0.125 - 0.25 lb a.i./Ac. This is especially effective against escaped winter annuals in the smartweed, composite, and legume plant families. Glyphosate (Roundup 4L). Applied in directed or shielded sprays at a rate of 0.75 - 1.5 lb a.i./Ac, or 1% (v:v) in spot sprays. Woody plants, such as poplar and sumac. Available Chemical Control Glyphosate (Roundup 4L). Applied in a directed spray at a rate of 1 - 1.5 lb a.i./Ac, 1% (v:v) in a spot spray, or 25% (v:v) with a wick wiper applicator. |
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