white fungus on soil = seed death?

[Grandad]

Anyone come across a white fuzzy fungus that grows on the top of soil?

Can this kill seeds after they've been germinated?

Anyone know how to get rid of this?

Any help would be appreciated.

 

[MynameStitch]

You got pictures?

WHat is your RH? What size pots are the seedlings in? How often are you watering?

 

[reaperz]

yes/no?

 

[Grandad]

Hi mynamestitch- thanks for taking an interest in this!

6 from 6 from the first lot didnt come up through the soil- although 5 of these had germinated using the paper towel method. Sensi say the seeds are viable once they crack.

I changed the soil when I saw the fungus and the first 6 hadnt grown- the original bag I used had been in the back garden for the summer so I thought it might have been contaminated.

I'm worried now that the fungus might have spread to the new pots- they were beside each other for the past few days.

These seeds were expensive. I need to save the rest. They are growing slowly (three days after germ most still have quite small root tips- only one has grown an inch)

This is what it looks like.

 

[Grandad]

pots are 5 inches. watered throughly at the start. none after that.

I normally get most to germinate.

 

[HeadyPete]

Try some more ventilation on your seedlings.

 

[MynameStitch]

THat looks like mold...... where is your grow? you got good ventilation?
WHat is your humidity?
How big is the pot you have that seed in? Take a picture of the pot...... what soil mixture are you using?

Did you reuse the pots that had the previous soil in them?

 

[Grandad]

These are planted in good quality potting soil with John Innes- this is marked for general use, growing seedlings etc. The soil in these pots is a fresh bag that I bought after the first batch went bad, and the fungal growth I showed you last time is not developing here.


Humidity is high here at the moment- autumn is in full swing at 52N, I cant tel ll you exactly what it is though

Here is what the pots look like.



I dont seem to be having much luck with the other 8 that were planted.
They all germinated before being planted (about 4 days ago), but seem to have stopped growing.

this one here is the most developed but now seems dead (dont worry it was under the surface). You can barely see a white scummy material here on the shell.



I have nine seeds left- I have one last shot with these so I need advice on how to correct whatever is going wrong. as I said I normally dont have problems like this but so far I have used 16 out of 25 seeds and dont seem to have had any luck.

Anyone had experience like this before? Is the problem maybe with the seeds or is it the environment seeing as they are all cracking at least?
Would mixing a teaspoon of bleach per cup with all water maybe work?

 

[HeadyPete]

Yes the mold/fungus killed your seedlings. You need a fan on low to keep a gentle breeze on the pots/seedlings to prevent humidity at soil level from raising to the point it encourages mold and fungus. That soil at the top is soaking wet. The swaying action of the seedlings also helps build a tough strong stem.

Using a seedling heat mat may increase your success and help combat damping off.

Another tip. Put more lighting on those seedlings after they pop the surface. With that one tube the seedlings will stretch, growing lanky and may fall over from a weak stem. Try a couple 27 w cool blue cfls to give more light.

 

[HeadyPete]

Damping-off generally refers to sudden plant death in the seedling stage due to the attack of fungi (see figure 1). These fungi are soilborne and are stimulated to grow and infect the seed or seedling by nutrients released from a germinating seed. However, seedlings may be injured or killed by something other than fungi, for example, toxic materials in the soil, excess or deficient soil moisture, seed defects, temperature extremes, toxic gases in the air, etc. A correct diagnosis is the key to effective control measures.

Figure 1. A seedling infected with damping-off fungi. Note the stem constriction near the soil line, a symptom characteristically associated with damping-off. This phase of the disease is called postemergence damping-off.

Figure 2. Seedlings grown in a container of soil infested with damping-off fungi.
Occurrence and Importance

Damping-off disease of seedlings is widely distributed and is a problem on a worldwide basis. It occurs in most soils, temperate and tropical climates, and in greenhouses. The disease affects seeds and seedlings of various crops. The amount of damage the disease causes to seedlings depends on the fungus, soil moisture, and temperature. Normally, however, cool wet soils favor development of the disease. Seedlings in seedbeds often are completely destroyed by damping-off, or they die after transplanting. Frequently, germinating seeds are killed by damping-off fungi before they emerge from the ground, which accounts for poor stands in many crops. Older plants are seldom killed by damping-off fungi mainly because the development of secondary stem tissue forms a protective barrier and limits fungal penetration. However, portions of the roots and stems still can be attacked, resulting in poor growth and reduced yields.
Symptoms

When seeds are planted in infested soils, damping-off fungi may attack them at any stage. The damping-off fungi may attack the seed prior to germination, or they may attack after the seed has germinated but before the seedling has emerged above the soil line. Infected seed becomes soft and mushy turning a brown to black color, and it eventually disintegrates. Seeds that have germinated and become infected develop water-soaked spots that enlarge and turn brown. The infected tissue collapses, resulting in death of the seedling. Penetration and death of seeds before they emerge is termed preemergence damping-off.

Seedlings that have emerged are usually attacked at or below the soil line. The organism can easily penetrate the young soft stem tissue. The infected stem portion becomes discolored and begins to shrink. As this occurs, the supportive strength of the stem's invaded portion is lost, and the seedling topples over (see figures 1 and 2). The fungi continue to invade the remaining portion of the seedling, resulting in death. This phase of the disease is termed postemergence damping-off.

Older established plants also can be attacked by damping-off fungi. Usually the new developing rootlets are infected, resulting in root rot. Infected plants show symptoms of wilting and poor growth.
Control

Proper conditions for seed germination and seedling emergence also favor vigorous growth of fungi that cause damping-off. Seed and roots must be kept moist and warm until the roots have penetrated the soil and the seedlings have emerged. As the seedlings continue to grow, moisture at the soil surface can be decreased, and the damping-off fungi then will have less of an advantage. When watering, thoroughly saturate the soil and then apply no more water until soil approaches the point at which plants wilt. This procedure will keep surface soil dry for a maximum time. Avoid frequent sprinkling because this generally keeps surface soil too moist and promotes fungal growth.

Damping-off may not occur at a location for many years and then be devastating in one season. Such situations sometimes can be traced to a change in crops or plant varieties, a change of source of soil, or some change in cultural practice. Prior to initiating any changes, it would be wise to test the intended changes on a small scale before the main planting is done.

Control measures for damping-off fall into several categories depending on the facilities available and whether preventive measures are to be used after the trouble has begun. Preventive measures are much preferred, but make preparations for emergencies. Preventive measures are based on eliminating fungi that cause damping-off or providing chemical barriers to prevent the fungi from growing in the planting medium.
Pasteurization of Soils

Soil for growing transplants in flats can be steam pasteurized. If steam is used, the entire soil mass should be maintained at a temperature of 160 degrees F for 30 minutes.

The home gardener obviously does not have facilities to steam soil; however, pasteurized, packaged soil mix is available from many garden centers. To prevent soil recontamination, all items such as tools, pots, and flats, etc., must be clean. The items can be cleaned in hot water (160 degrees F for 30 minutes) or in a chlorine bleach solution (1 part bleach to 9 parts water; soak for 30 minutes). It is important to use fresh chlorine bleach-water solutions.
Seed Treatment

Since the possibility exists for recontamination of pasteurized soil and thus for damping-off losses to occur, a fungicide seed treatment should be considered to minimize losses. Examples of fungicides used as seed treatments include Thiram and Captan.

Various cultural practices may be helpful in reducing the amount of infection. Fungicide-treated seed that is sown directly, or seedlings that are planted in garden plots or larger fields, should be planted only on well-drained soils. Avoid crowding the plants, and plant when temperatures are favorable for rapid plant growth. Avoid heavy applications of nitrogen fertilizers, and do not plant the same crop in the same field for more than two consecutive years.

http://www.extension.umn.edu/distribution/horticulture/DG1167.html

 

[Grandad]

"Infected seed becomes soft and mushy turning a brown to black color, and it eventually disintegrates. Seeds that have germinated and become infected develop water-soaked spots that enlarge and turn brown. The infected tissue collapses, resulting in death of the seedling"

heady Pete this has a ring of familiarity. thanks for the info.

much appreciated.

Excelatit I'm also learning the hard (and expensive) way. I will try bleach and see if I can sterilise things.

9 seeds left. Out of 25 that cost €210. Bollix.