Job offersmore »
- Managing Grower - Australia
- Senior Grower - Talbotville, Ontario, Canada
- Operations Manager - Fresh Produce
- Senior Account Manager Retail - Netherlands
- Supply Allocation and Inventory Manager - Fresh Produce, Italy
- Senior Grower - Katunga, Australia
- Key Account Manager - Netherlands
- Accountmanager aardappelinkoop BelgiŽ / Frankrijk
- International Retail Manager - Netherlands
- Quality Assurance Team EA Region -Antwerp- Quality Supervisor, Belgium
Last commentsmore »
- India: Government gives 50% subsidy on a poly house (955)
- UK: What's in season at the New Covent Garden Flower Market (4)
- Will sea freight be an alternative to Latin American air freight? (27)
- US: AFE educational grant applications due June 1 (4)
- Women's Day: "Russian market is growing up" (2)
- Danish greens grower expands with first own bred peperomias (1)
- Export stop Australia as of March 1 2018 (1)
- Colombia, Kenya and China: What's their recipe for success? (1)
- "Proven Winners is just getting started" (1)
- Market reports: solid research or wild guesses? (4)
Top 5 - yesterday
- No news has been published yesterday.
Top 5 - last week
Top 5 - last month
Exchange ratesmore »
Nutritional factsheet geraniumsGeraniums require medium levels of fertilization, growing best with 150 to 200 ppm N. Optimal substrate pH values are between 5.8 and 6.5. Geraniums are susceptible to both low and high pH disorders, developing iron (Fe) and manganese (Mn) toxicity at low pH and Fe deficiency at low pH.
Geraniums require medium levels of fertility. Growers should provide fertilization at 150 to 200 ppm N. Low soluble salts [referred to as electrical conductivity (EC)] from inadequate fertilization can cause yellowing (chlorosis) or reddening on the lower foliage. High EC is an issue during propagation, as cuttings and seedlings are sensitive to root burning (plasmolysis) and lower leaf browning (necrosis). For this reason, fertilization should be maintained at 100 ppm N during propagation (Dole and Wilkins, 2005). Excess salts may build up in the substrate during stock plant production, leading to plasmolysis and lower leaf necrosis. Frequent leaching with clear water should be implemented to control EC and prevent symptom development (Dole and Wilkins, 2005).
Substrate pH should be maintained between 5.8 and 6.5. Values beyond this range commonly lead to high or low pH induced nutritional disorders (Whipker and Henry, 2017). High pH inhibits iron (Fe) uptake, causing interveinal chlorosis of the upper foliage. Low pH causes excessive uptake of Fe and manganese (Mn), which leads to toxicity symptom development. Symptoms of Fe and Mn toxicity include a lower leaf bronzing with dark brown to black spotting.
Foliar Fe and Mn concentrations should remain below 500 ppm (Dole and Wilkins, 2005). Previous reports of low pH induced Fe and Mn toxicity document foliar concentrations of these two elements to be ~10◊ higher than in asymptomatic plants (Henry and Whipker, 2016). Monitoring substrate pH and periodic tissue sampling can help to determine if symptoms are due to high or low Fe and Mn. Iron deficiency can be remedied with an application of Fe chelate, while Fe and Mn toxicity can be remedied by providing flowable lime to raise the pH.
Download the factsheet from eGro.
Publication date: 1/30/2018
Other news in this sector:
Leave a comment: (max. 500 characters)
- All comments which are not related to the article contents will be removed.
- All comments with non-related commercial content, will be removed.
- All comments with offensive language, will be removed.