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Zinnias are wonderful sources the pollen and also nectar because that many useful insects; therefore, that is no recommended the insecticides, various other than insecticidal soap, be used to manage damaging mite and insect pests. Rather than depending exclusively on pesticides, proper society (soil preparation, fertilizers, irrigation, mulch, optimum tree spacing, and adequate sunlight) is the better method for staying clear of insect and an illness problems.

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Zinnias have few insect pests, yet aphids, spider mites, and whiteflies may damage plants, especially throughout hot, dry weather. Aphids and spider mites can be hosed turn off the plants through a strong stream that water. Because spider mites prosper in hot, dried weather, reduce drought anxiety with supplemental watering will assist prevent one infestation. Spray applications that insecticidal soap may be applied to control spider mites, aphids, and whiteflies, but always spray flowering plants in the so late evening to prevent harming valuable insects or hummingbirds. Insecticidal soap sprays must be directed at the reduced leaf surface where numerous pests feed. Check out Table 1 for instances of insecticidal soap products. For an ext information around the use of insecticidal soap, check out historicsweetsballroom.com 2771, Insecticidal Soaps because that Garden insect Control.

Disease avoidance & Control

Most illness may it is in prevented when zinnias space watered and cared because that properly. Zinnias grow finest in complete sun every day; however, they may be more prone to leaf spot illness in partial shade. That is necessary to keep the foliage dry to discourage bacterial and also fungal diseases. Therefore, that is best to constantly water near the base of the plants. If overhead watering is used, irrigate throughout the early on morning hrs to allow the leaves to dry easily in the morning sunlight. An illness incidence is greater if plants room watered in the so late afternoon or evening, hence causing the leaves to remain wet longer. These conditions carry out the perfect atmosphere for both bacterial and fungal disease development.

Alternate using zinnias with different bedding plant species for a year or two to reduce an illness incidence. Prompt remove of any kind of highly pest-infested or disease-infected tree will alleviate pest and an illness spread. In ~ the finish of the cultivation season, remove all tree debris to reduce the carry-over that fungal condition inoculum (the microorganism responsible for the infection). This will certainly lessen or hold-up the incident of diseases the adhering to year. Infected seed may also be a resource of this diseases; therefore, execute not conserve seed because that sowing the following year if there has actually been an episode of leaf spot diseases.


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These zinnias have end up being infected through powdery mildew (Golovinomyces cichoracearum).Mary Ann Hansen, Virginia Polytechnic academy & State University, Bugwood.org


Powdery Mildew: Powdery mildew is a fungal condition (Golovinomyces cichoracearum) that shows up primarily on tree foliage however may additionally infect flowers and also stems. This an illness appears together a grayish-white, powdery coating top top zinnias. Exercise good cultural methods. However, if fungicides are required, there are numerous that are an extremely effective. These include copper-based fungicides, horticultural oil through baking soda, sulfur, myclobutanil, propiconazole, tebuconazole, and also thiophanate methyl. The last four detailed are the most reliable for powdery mildew control. Under problems of disease development, spray tree weekly. Constantly spray fungicides in the late evening to minimize the impact on pollinating insects. See Table 1 for instances of brands and products. Follow brand directions for mixing and use. For much more information on powdery mildew and also control, view historicsweetsballroom.com 2049, Powdery Mildew.


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Alternaria sheet spot of zinnia (Alternaria zinniae) starts as small, dark reddish, circular point out that quickly expand and also become irregularly shaped v grayish-white centers.John Hartman, college of Kentucky, Bugwood.org


Alternaria sheet Spot: The fungus Alternaria zinnia causes a sheet spot ~ above zinnias the starts together small, dark reddish, circular spots that promptly expand and also become irregularly shaped with grayish-white centers. As the spots come to be larger, castle may develop dark concentric rings in the centers. The center of these leaf spots may ultimately tear, fall out, and also leave behind feet in the leaves. Major infections cause the pipeline to rotate brown quickly and shrivel. Infections take place not just on foliage but likewise on beam flowers, which will certainly wither and produce lesions ~ above stems, which often become girdled and also finally wilt. Seed indigenous infected plants deserve to spread this sheet spot disease. Spray plants following rainy periods, together rainy problems increase condition occurrence and spread. The much better fungicides to manage Alternaria sheet spot space chlorothalonil, copper fungicides, and also mancozeb. See Table 1 for instances of brands and also products containing these fungicides. Follow brand directions because that mixing and use. Do not use thiophanate methyl fungicides, together these are ineffective. Constantly spray flower ornamentals in the late evening.


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Bacterial leaf spot of zinnia (Xanthomonas campestris pv. zinniae) is a common disease, which occurs under problems of expanded leaf wetness.Penn State Dept. Of tree Pathology & eco-friendly Microbiology Archives, Bugwood.org


Bacterial leaf Spot: Xanthomonas campestris pv. zinniae is the causal agent of bacterial leaf spot the zinnias, and also the symptoms of infection are purplish spots the usually continue to be small, yet they become angular in shape. Spots may construct a yellow halo. Spray plants weekly with a copper fungicide adhering to periods of leaf wetness to reduce condition incidence, as copper fungicides are likewise effective against many bacterial diseases. Check out Table 1 for examples of brands and also products containing copper. Follow label directions for mixing and also use. Always spray tree in bloom throughout the so late evening. Seed gathered from infected plants might spread bacterial sheet spot.


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Cercospora sheet Spot: This fungal leaf spot, caused by Cercospora zinniae, occurs less commonly than Alternaria sheet spot, powdery mildew, or bacterial leaf spot, however it have the right to be simply as damaging. Cercospora sheet spots on foliage are typically reddish-purple, small, and also round v light gray to virtually white centers. These spots may coalesce (run together), and heavily infected leaves generally die. Spray together needed adhering to rainy durations with chlorothalonil, copper fungicides, or mancozeb. Watch Table 1 for instances of brands and also products with these fungicides and also follow brand directions because that mixing and use. Constantly spray flowering ornamentals in the so late evening.


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Aster Yellows: Aster yellow is led to by a phytoplasma and also is similar to a bacterium. That is brought by aster leafhoppers (Macrosteles quadrilineatus), which room insects the feed on the sap that the plants. As they feed, castle inject the phytoplasma right into the vascular device of the zinnia and cause the arising flowers to end up being deformed. There is no control an approach once the flowers have actually been infected, and also plants v symptoms should be timeless removed and also discarded in the trash. Fortunately, aster yellows is not extremely common.

Table 1. Fungicide & Insecticide assets for condition & Pest regulate on Zinnias

Active IngredientExamples of commodities
ChlorothalonilBonide Fung-onil Multi-purpose Fungicide Concentrate; & RTU1
Ferti-lome large Spectrum see & Garden Fungicide Concentrate; & RTU1
GardenTech Daconil Fungicide Concentrate; & RTU1
Hi-Yield Vegetable, Flower, Fruit & Ornamental Fungicide Concentrate
Ortho MAX Garden condition Control Concentrate
Southern Ag liquid Ornamental & vegetables Fungicide Concentrate
Tiger Brand Daconil Concentrate
Copper-based FungicidesBonide Copper Fungicide Spray or Dust
Bonide fluid Copper Concentrate; & RTU1
Camelot O Fungicide/ Bactericide Concentrate
Espoma essential Copper Soap RTU1
Monterey fluid Copper Fungicide RTU1
Monterey Liqui-Cop Fungicide Concentrate; & RTS2
Natural security Copper Soap liquid Fungicide Concentrate; & RTU
Southern Ag liquid Copper Fungicide Concentrate
Horticultural Oil3Ferti-lome Horticultural Oil Spray Concentrate; & RTS2
Bonide All seasons Spray Oil Concentrate; & RTS2; & RTU1
Southern Ag ParaFine Horticultural Oil Concentrate
Monterey Horticultural Oil Concentrate; & RTS2; & RTU1
Safer Brand Horticultural & Dormant Spray Oil Concentrate
Summit Year ring Spray Oil Concentrate; & RTU1
Insecticidal SoapBonide Insecticidal Soap RTU1
Espoma organic Insect Soap RTU1
Garden for sure Insecticidal Soap Insect Killer RTU1
Miracle Gro Nature’s treatment Insecticidal Soap RTU1
Natria Insecticidal Soap RTU1
Natural guard Insecticidal Soap Concentrate
Safer Brand Insect death Soap Concentrate
Whitney ranches Insecticidal Soap RTU1
MyclobutanilSpectracide Immunox Multi-Purpose Fungicide Concentrate
Ferti-lome F protect against Lawn & Garden Fungicide Concentrate
Monterey Fungi-Max
PropiconazoleBanner Maxx Fungicide
Bonide infuse Concentrate; & RTS2
Ferti-lome fluid Systemic Fungicide II Concentrate; & RTS2
Sulfur4Bonide Sulfur tree Fungicide (dust or spray)
Ferti-lome Dusting Sulfur (also wettable for spray)
Hi-Yield Wettable Dusting Sulfur
Safer Brand Garden Fungicide Concentrate
Southern Ag Wettable or Dusting Sulfur
TebuconazoleBayer BioAdvanced condition Control for Roses, flowers & Shrubs Concentrate
Thiophanate MethylCleary’s 3336-WP Turf & Ornamental Fungicide
Southern Ag Thiomyl Systemic Fungicide
1 RTU = a pre-mixed spray bottle.2 RTS = a hose-end spray bottle.3 three tablespoons that horticultural oil in a gallon the water plus 3 tablespoons that baking soda. Never use an oil spray within 2 weeks of a sulfur spray, and do not use oil sprays when temperatures are over 90 °F or come drought-stressed plants.4 carry out not use sulfur if temperature is better than 85 ºF or to dryness stressed plants. Perform not usage sulfur in mix with, or within 2 weeks before or ~ the use of horticultural oil treatments. Sulfur will additionally control mites.

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Author(s)

Barbara H. Smith, historicsweetsballroom.com Horticulture extension Agent, historicsweetsballroom.com UniversityJoey Williamson, PhD, historicsweetsballroom.com Horticulture extension Agent, historicsweetsballroom.com University

This details is supplied with the expertise that no discrimination is intended and no endorsement of brand name or registered trademarks by the historicsweetsballroom.com University participating Extension organization is implied, no one is any kind of discrimination intended by the exemption of assets or manufacturers not named. All recommendations are for south Carolina conditions and may not apply to other areas. Use pesticides just according come the direction on the label. All recommendations for pesticide use are for southern Carolina only and also were legit at the time of publication, yet the standing of registration and use patterns are subject to change by activity of state and federal regulation agencies. Follow all directions, precautions and restrictions that are listed.