Iris Thrips, Iridothrips iridis.

Nymphal stage: mil1cy white nymphs that feed on the inner surface of young leaves and leaf sheaths.
Adults: glistening, dark brown and winged, they overwinter in the crown of the plant.
A sucking insect.

Control:

Insecticidal soap. Malathion
Spinosad (marketed in gardens centers as Monterey Garden Insect Spray)

Aphids, Aphis sp.

As immatures, aphids appear as tiny tear drop shaped creatures with two horns on their rear end.
They may be white, green, red, yellow, black or brown in color. They are sucking insects that produce copious amounts of honeydew. This in turn attracts ants and black sooty mold.
When the population of immatures becomes high, and competi­tion for food develops, some of them will mature on to small, winged, fly-like organisms.

Control:

Hard spray of water.
Soapy water spray.
Beneficial insects, i.e. lady bugs, lacewings, etc. Malathion

Whitefly, Aleyrodes spiraedides Nymphal stage appears like a scale.

Adult stage is a tiny white fly.
A sucking insect.

Control:

Soapy water spray. Beneficial wasps. Yellow sticky traps. Malathion

Bacterial Soft Rot, Psuedommonas ssp., Erwinia carotovora

Bacterial in nature, these diseases attack the leaf bases and rhizomes of the plant. The problem is most easily identified by the foul odor that accompanies the problem. It is usually linked to problems with the Iris Borer. Symptoms include water-soaked margins around a borer hole in the leaf, wilting and dying of fans, and fans that fall over or are easily separated from the rhizome.

Control:

Prevent Iris Borer problems. Remove infected plants.
Avoid overwatering and over fertilizing, as this problem is exacerbated by warm, moist conditions.
On rhizomes that are salvageable, cut away infected tissues, and allow the surface to dry before re-planting.
Some luck has been experienced with dusting of the cleaned wounds with Comet (remember to test first).
Soal( rhizomes in 10% bleach solution BUT be sure to rinse. (this procedure is not suggested for Siberian Iris).
Plant high, in well-drained soil.
When planting, do not crowd or place in too shady of an area. Any equipment that is used in procedures should be· cleaned between cuts with 10% bleach or 70% alcohol.

Rhizome Rot, Botrynia convoluta, Sclerot;um rolfsii

These two fungal problems cause the rhizomes and leaf bases to rot. Characteristic signs are white fuzzy growth on the sur­face of the plant parts and the soil. These diseases lack the foul odor that accompanies Bacterial Soft Rot.

Prevention of Pest and Disease Problems

Many problems can be avoided with some very simple strategies:

1. 
   Any crop should be started with clean plant material. If purchasing new plants, inspect carefully to make sure that they are healthy.
2. 
   If sharing plants with others, again inspect thoroughly so that you don't introduce new problems into your yard or greenhouse.
3. 
   If a plant appears to have a problem, isolate it for a period of time and take appropriate control measures.
4. 
   Sanitation, sanitation, sanitation! This cannot be emphasized enough. Always begin with clean soil, clean pots, clean pruning equip, etc.
5. 
   Removal of dead or diseased plant material. Whether in the ground
   or in a pot, it ain't gonna revive! Get rid of it, and not to the compost pile. Diseased material that is not removed from the property or burned, is simply the next source of inoculums.
6. 
   Generally speaking, watering early in the day is best. This allows for
   water to move into the plant and excess to evaporate before temperatures , drop and fungal spores start to go wild.
7. 
   Spacing plants further apart helps to improve air circulation, which again, is helpful in preventing some fungal problems.
8. 
   Well drained soil can be helpful in the prevention of certain soil fungal diseases. Amend ground soils or prep potting soil to provide better drainage.
9. 
   If you have been working with an infected plant, sanitize your hands / tools before you work with another plant.
10. 
    If possible, select varieties that have fewer pest problems.

Isaiah 40:8
The grass withers and the flowers fade, but the Word of our God stands forever.  

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