This page lists alerts from the current season (vol. 11) and vol.10 from 2021.
For earlier seasons please click here for the archives dating back to 2012.
11.07 - Coleus Insect Photo Guide
This e-GRO Alert provides a photographic guide to coleus insects.
11.06 - Coleus Disease Photo Guide
This e-GRO Alert provides a photographic guide to coleus diseases.
11.05 - Coleus Physiological Disorder Photo Guide
This e-GRO Alert provides a photographic guide to coleus physiological disorders.
11.04 - Coleus Nutritional Disorder Photo Guide
This e-GRO Alert provides a photographic guide to coleus nutritional disorders.
11.03 - Hitting the IBA Sweet Spot to Improve Rooting
The use of IBA improves rooting efficiency, but too much can be detrimental. This Alert helps to diagnose excessive rates.
11.02 - Plant Growth Regulator Guide for Herbaceous Perennials Update
The latest edition of the Plant Growth Regulator Guide for Containerized Herbaceous Perennial Plants is now available. Thanks to the sponsor, Fine Americas, Inc., growers can download a free copy online and/or subscribers of GrowerTalks will receive a copy in the mail.
10.38 - Pansy problems: Leaf spot, powdery mildew, and Myrothecium crown rot
Pansies and violas are affected by numerous plant diseases including black root rot, Pythium root rot, powdery mildew, Botrytis blight, and Cercosporaleaf spot. During the winter and spring of 2020, there was also a major problem with Myrothecium crown rot.
10.37 - Unusual Leaf Spot on Poinsettia
While not commonly encountered on poinsettias, Corynespora cassiicola can cause brown leaf spots on leaves and bracts in conditions of high moisture and high humidity.
10.36 - Poinsettia Leaf and Stem Abnormalities
Given that poinsettias are propagated during the hottest months of the year and have a very long production time, they are prone to several pathogens, pests, and physiological disorders.
10.34 - Dodder (Cuscuta spp.): Orange, spaghetti-like growth
Dodder is a parasitic weed with orange, spaghetti-like growth that entwines around plants.
10.33 - Ornamental Cabbage and Kale Water Stress
Excessive wilting of the plants will result in lower leaf yellow and leaf drop.
10.32 - Ornamental Cabbage and Kale Coloration Tips
Coloration of ornamental cabbage and kale is primarily influenced by temperature. A few production practices can help enhance the intensity of coloration, but discontinuing fertilization is not one of them.
10.31 - Summer Weather Patterns Can Influence Irrigation Water Quality
Weather conditions and drought can affect the quality of your irrigation water. Increased alkalinity levels in your irrigation water may be linked to water use.
10.30 - Root Rot in Garden Mums
Small and off-color mums may be a sign of root rot.
10.28 - Garden Mums: Crown Buds Induced by Cool Night Temperatures
Fall garden mum production typically occurs outdoors exposing plants to seasonal environmental conditions. When plants are exposed to several nights of <60 °F (<15.5 °C), premature bud formation or crown buds can be induced.
10.27 - The green you do not want in the greenhouse: Algae
Brief description: A review about practices and products to control algae in greenhouses.
10.26 - White Rust on Portulaca
White rust is not a true rust nor a fungal disease. It is an oomycete disease, and it was recently seen infecting moss-rose purslane (Portulaca grandiflora) in hanging baskets.
10.25 - Taking a More Holistic Approach to Fungus Gnat Management
Fungus gnats can impact crop quality and spread Pythium in greenhouses
10.24 - Pandemic Assistance Programs for Greenhouses and Nurseries
Nearly all floriculture and nursery operations have been impacted by the pandemic. Learn more about USDA programs that can assist producers in challenging times.
10.23 - Leaf-Curling Plum Aphid: A Pest to Watch
Leaf-curling plum aphid, Brachycaudus helichrysi, can cause distortion, stunting of new growth on plants in the Asteraceae.
10.22 - White Mold (Sclerotinia) on Coleus
Description: Coleus plants with white cottony-like growth, stem and leaf rot, and small, hard, black sclerotia were observed. This Alert describes and provides photos of symptoms observed on coleus caused by white mold (Sclerotinia sp.) also referred to as Sclerotinia stem rot or cottony soft rot. To diagnose white mold, submit plant samples to your preferred diagnostic lab.
10.21 - Scouting and Treatment of Gray Mold in Greenhouse Crops
Peak color in the greenhouse coincides with cloudy, damp weather that creates a favorable environment for the fungus Botrytis cinerea, which causes gray mold on many greenhouse ornamentals. This Alert provides tips for scouting and management of gray mold and gives an example fungicide treatment plan for when disease pressure is high.
10.20 - Begonia and Vinca Sensitivity to Paclobutrazol
Plant growth regulators (PGRs) can be successfully used to control growth or induce lateral branching of many bedding plant species, but some may be ‘sensitive’ to the PGR active ingredient. This Alert demonstrates PGR sensitivity for fibrous begonia and vinca where an accidental paclobutrazol drench application resulted in stunted plants, chlorotic (yellowing) leaves, and black spotting.
10.19 - Prevent Chilling Injury
The pandemic, coupled with the cold winter has consumers demanding annuals, herb, and vegetable transplants weeks before the last average frost date. As growers, you obviously want to cash in and take advantage of these impulse purchases. But we all know this is risky! What can you do to prevent losses during those unpredictable cold snaps that occur in April and even into May? In this alert, we will provide some tips on how to protect your crops and provide you with a list of cold hardy plants you should be selling.
10.18 - GR Drenches for Growth Control
Trying to control the growth of all your different spring crops can be a challenge. With so much diversity in our greenhouses, heads can spin trying to keep growth regulated effectively and efficiently. Using PGR drenches can help you this spring, and this Alert will focus on how to do it effectively.
10.17 - Lily Basal Rot
Lily basal rot caused by Fusarium oxysporum f. sp. lilii can cause crop losses in Easter Lilies.
10.16 - Plant Disease Resistance, Reviewed
Defining and understanding plant resistance, susceptibility, immunity.
10.15 - Troubleshooting Ipomoea
Warm season annuals such as ipomoea can be challenged with cloudy weather.
10.14 - Ask an Entomologist
With the pandemic has come even greater demand for diagnostic lab support. Read about some recent issues and what some entomologists do to support our horticulture industries.
10.13 - Bacterial leaf spot diseases are prevalent in wet greenhouses
Wet, humid, overcast weather outside favors plant disease development inside greenhouses because plant foliage and soil remain wet for extended periods of time. Plant wetness within warm greenhouses coupled with young, succulent seedlings and cuttings in production is a recipe for disease development, particularly bacterial leaf spots diseases, which have been widely seen within greenhouses affecting bedding and foliage plants.
10.12 - Cashing in on the Top Four Gardening Motivations of 2020
The spring of 2021 is here! During 2020, despite a very difficult start, many plant retailers had an excellent year – even record-breaking. Why?
10.11 - Interpreting Water Quality Analysis Reports
The quality of irrigation water is crucial to develop nutrient programs that are compatible with the crops’ needs. In this Alert, we will discuss how to interpret the water quality analysis reports to evaluate chemical aspects of water quality that affect nutrient programs.
10.10 - PourThru Method for Large Containerized Crops
The PourThru method is a great procedure to determine the nutritional status of containerized crops. This Alert outlines the steps need to perform a PourThru on larger containers for mix combination planters, herbaceous perennials, and nursery and specialty crops.
10.09 - Sampling Irrigation Water for Routine Lab Analysis
Irrigation sampling is an important nutrient monitoring practice to determine water quality such as pH, electrical conductivity (EC), alkalinity, and available dissolved nutrients. Assessing irrigation water quality will help refine alkalinity management and fertility programs and define limited or excessive nutrients for the appropriate corrective procedure.
10.08 - _Elevated EC Symptomology
Lower leaf necrosis can develop in stevia if the substrate electrical conductivity (EC) is elevated.
10.07 - Stevia: High Substrate pH
Stevia can develop interveinal chlorosis of the upper foliage if the substrate pH is too high.
10.06 - Calonectria root, crown, and cutting rots are less common, but just as damaging
Besides the more common pathogens causing root disease in greenhouse crops, there are other lesser known but equally destructive pathogens affecting specific crops. One example is Calonectria spathiphylli that causes root and petiole rot of Spathiphyllum. Other Calonectria sp. cause root, crown, and cutting rots on woody and herbaceous plants.
10.05 - Aphids in Unexpected Places
Over the past year I had some interesting samples of and questions about aphids, so as winter transitions to spring I’ll use the opportunity to review some of the less common species we’ve encountered in greenhouses over the years while issuing the standard reminder to watch for early signs and respond while infestations are still small in size and area.
10.04 - Who Said That Pansies Were Easy?
Pansies would seem to be an uncomplicated or easy crop….but then the leaves started to yellow…..
10.03 - Powdery Mildew on Succulents Is Not What You Would Expect
Powdery mildew on succulents can appear more like sun scald or edema. In this alert, we will show you what to look for and the fungicides labeled to treat powdery mildew. Remember, when in doubt, submit a sample to a diagnostic lab for confirmation.
10.02 - PGR Guide for Annuals
The 72-page Plant Growth Regulator Guide for Annuals publication has been updated for the 2021-2022 season.
10.01 - Sampling Substrates for Routine or Diagnostic Lab Analysis
Substrate sampling for routine or diagnostic lab analysis is an important nutrient monitoring practice to assess substrate chemical properties including pH, soluble salts, and nutrient status.