Fungus gnats were a problem in some greenhouses this week. During cool, cloudy weather and/or cool greenhouse temperatures media stays moist, encouraging the growth of algae on the media surface as well as fungus gnats. Adult fungus gnats are attracted to newly planted crops, where the females lay their eggs in the crevices of the moist growing media. Eggs hatch into damaging larvae that feed upon tender, young roots; the developing callus of cuttings, and even bore into the stems of succulent plants such as sedum, coleus and geraniums.
Monitor pH and nutrition on geranium crops. Using 20-10-20 constant feed for all crops could lead to low pH on geraniums resulting in iron/manganese toxicity symptoms. If the problem is not corrected early in the crop cycle, the crop will likely not recover in time for sales. This is a problem to prevent.
If media remains wet, plants are more prone to root rot. At least once a week, randomly select plants to inspect roots to monitor the health of the crop. If roots do not look healthy, conduct a soil test for soluble salts and test roots for disease, either by sending samples to a lab or by using on-site test kits. Sometimes high soluble salts levels occur when root function is impaired by disease or physical damage. It is difficult to diagnose soluble salts without an EC test. Often nutrient deficiencies and root diseases cause the same symptoms.
Downy mildew has been observed on basil. If you suspect your basil plants are suffering from a nutrient deficiency, you may want to inspect plants more carefully, for Downy Mildew. Symptoms are similar especially before visible spores develop.
The arrival of cool temperatures reminds us that it won't be long before perennials will need covering for winter protection. Overwintering perennials for the first time? The process for successful overwintering begins with healthy plants.
It has been an interesting winter. Given the warm temperatures this year, growers are advised to open up overwintering greenhouses on warm days to ventilate. Either roll up sides, open doors, use fans, depending on the type of overwintering greenhouse. Ventilating will lower the relative humidity. Greenhouses that are closed up will result in moisture buildup and encourage plant diseases to develop. Also, take time to inspect plants in overwintering houses, particularly for disease and injury caused by rodents.
Sometimes poinsettias are prone to lateral stem breakage. The crop may look healthy and the roots look good, yet an occasional branch will wilt for no apparent reason. There are several possible reasons for this condition. Varieties can differ in susceptibility. The most sensitive plants are those with lower laterals that grow perpendicular to the stem.
In 2013 Easter Sunday falls on March 31. This is considered an early date Easter but the schedule allows adequate time for the full 23 week program. To stay on this schedule, growers will need to begin the process by October 21, 2012 and maintain proper cooling and forcing temperatures throughout. This requires that bulbs arrive on time and in good shape and that you are prepared to handle them immediately. The key steps in the forcing program for pot-cooled bulbs include a three-week rooting period (at 63F) followed by six weeks of bulb cooling (at 40-45F).
Given the recent warm temperatures, growers are advised to open up overwintering greenhouses on warm days to ventilate. Either roll up sides, open doors, use fans, depending on the type of overwintering greenhouse. Ventilating will lower the relative humidity help prevent botrytis. Greenhouses that are closed up will result in moisture buildup and encourage plant diseases to develop.
Liverworts ( Marchantia polymorpha ) are branching, ribbon-like plants lacking distinct roots, stems and leaves. They reproduce by spores and vegetatively. Stalked, umbrella-like structures release spores. Small, bud-like branches that are produced in cup-like structures on the surface of the plant also help spread liverworts. Liverworts thrive in conditions of high fertility, moisture and high humidity and require moister conditions than mosses.