question on research on tarsonemid mites

aacor11March 9, 2013

I have been looking for research on tarsonemid mites in an effort to understand what could be done to control them

and I found this research on steneotarsonemus (is this the hippeastrum mite?)
(www.daff.gov.au bulbdatasheet)

"In the UK, S. laticeps is a major pest of narcissus cultivation and is most severe in forced bulbs. Infested bulbs show a considerable reduction in flower yield and quality. Feeding damage caused by this mite appears as reddish streaks and spots at the base of developing leaves and stems. The streaks elongate as growth proceeds and leaves become distorted and can fail to grow in badly affected bulbs. Red marks can be seen inside the bulb where the mites are feeding.

This species reproduces throughout the year and there are several overlapping generations. The rate of development is dependent on temperature and at 14-16oC under humid conditions, the life cycle can be completed in two weeks. Most eggs were laid at 20oC (about 30 per female), the highest percentage egg hatch occurred at 15oC (93%) and development from egg to adult was fastest at 20oC (15 days). At temperatures outside of 10 to 25oC, either development was very slow (51 days) or no adults were produced."

If 25C is enough to stop them, why do I need to buy acaricides, can't I put the pots on a heater (which brings the temperature in the pot at about 30C)?

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blancawing

Hello aacor11,

Yes, Steneotarsonermus laticeps is also referred to as the tarsonemid mite and the bulb scale mite.

I can't answer your question about putting your pots on a heater. However, I can refer you to Veronica Read's advice, which is included in her book "Hippeastrum: The Gardener's Amaryllis."

"Mites are active betwen 50 and 68à ¼ F (10-20à ¼ C) becoming motionless at 38à ¼ F (3.5à ¼ C), at which temperature eggs will cease to hatch. Mites will be killed at temperatures over 100à ¼ F (38à ¼ C)."

Ms. Read also writes, they "can cause extensive damage which may prove fatal and, unless diagnosed at an early stage, can result in the total destruction of a crop or collection. By the time the bright orange-red streaks, stripes and scars are visible, infestation is severe and bulbs should be destroyed immediately. If cultivating plants indoors, any remaining healthy plants should be isolated immediately and all known and possible mite-infested areas thoroughly cleaned and disinfected. Depending on if and where bulbs had been stored prior to planting and where the plants were cultivated, this may necessitate disinfecting cupboards, steam-cleaning carpets and washing or dry cleaning curtains and other furnishings. Once deprived of their food source, the mites will quickly die, but if cultivating the plants in the home, it is advisable not to reintroduce existing or fresh bulbs for 6 months until you are sure that all traces of the mites have been eradicated."

I hope that this information will be helpful to you. Good luck with eradicating these nearly invisible, minute arachnids that are related to ticks from your Hippeastrum collection. The adults have four pairs of legs!

-Blanca

This post was edited by blancawing on Sat, Mar 9, 13 at 17:11

    Bookmark   March 9, 2013 at 5:01PM
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aacor11

Thank you very much for the detailed and precious information! It is really important to understand the pest well in order to fight it with the best means.

I do have a couple of questions left... Pouring a heavy oil (vaseline or liquid coconut) in the cracks between the leaves and the bulb or on top just to seal all possible air sources would help kill the mites? Don't they need to breathe? Could I just submerge the bulbs and leaves for 36 hours to kill the mites?

Alcohol is not an option? (I suppose it reduces the plant's ability to feed?)

    Bookmark   March 13, 2013 at 1:39PM
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aacor11

If I have the bulbs in clay pellets, temperatures of 38C would not dry the roots? (there are no roots right now)

Is it better to heat the bulbs in clay pellets or in potting media...? I plan to put them on a heater if the cold treatment doesn't kill the mites; so far I left them in the cold (3C to -5C) for 48h.

Was that terribly wrong?

    Bookmark   March 15, 2013 at 4:58AM
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browneyedsusan_gw(8a)

A dilute dish-soap solution kills roaches and most insects . Because soap reduces the surface tension of water it can enter through the spiracles of insects into their trachea (breathing tubes), causing them to suffocate. Just a factoid from a college zoology class that I had years ago, that came to mind. I think most bulbs can be submerged in a dilute soap solution for a few minutes without harm.

Susan.

    Bookmark   March 15, 2013 at 12:26PM
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haweha

Diluted Tensid Solution does not kill them.
They survive in concentrated isopropanol even - for HOURS. So, alcohols are not an option for bulbs. Neither are Oils, the mites hide too deeply beween the leaf bases.
Hot water treatment on bulbs, before storage for the Reposal period, eradicates the pest. However, re-infestation from contaminated environment is soon to be expected, Veronica indicates this correctly by suggesting keeping rooms for months w/out Hippeastrum and other Amaryllids respectively.
I use repeated sprayings with Dimethoat (400g/L) diluted at 2.5 mL/L on the growing crop and on the decapitated bulbs before and during storage which method is not eradicative.

    Bookmark   March 16, 2013 at 4:12AM
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aacor11

Unfortunately, Sir Hans was right.
Oil does not kill the mites, it does kill the bulbs though... covering the leaves with a non breathable film. Heat seems to be the only solution.

My heater goes up to 50C on its surface, damage to the bulb was minimal (the outer layer was affected in 2 places after the bulbs were left on the heater for 36 hours. I am not sure if they got reinfested again from surfaces etc. or if the temperature in the core of the bulb went high enough to kill mites and fungus. (the bulb was rotting from inside)

As I do not have fungicides, I suppose I can't cut it and remove the rotten parts. Or should I anyway?
I wanted to put it back on the heater in some shop bought orchid mix without watering the mix. That way the mix would hopefully reach a higher temperature kill the fungus and the mites in the process...

My lack of knowledge is terrible, especially in biology. It is a pity as I was hoping this whole experiment could help find alternative way to fight the mites.

    Bookmark   March 17, 2013 at 1:14PM
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npublici(Zephyrhills,Fl)

I have submerge treated bulbs with a ten percent chlorox solution,for 15 minutes,to kill fungus and bacteria.In the US chlorox is sold as a five percent sodium hypochlorite content in ninty five percent water.It was effective.I had previously cleaned out the bulbs with a pressurized water hose,outside.
Del

    Bookmark   March 21, 2013 at 8:22PM
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lbphilly(6)

Question for npublici: when you say a ten percent Clorox solution, do you mean one part Clorox as it comes out of the bottle to nine parts water? And does this also kill mites?

    Bookmark   June 1, 2014 at 10:56AM
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