Scouting Notes - June 2007

Control thrips to limit INSV. As more flowers bloom and temperatures increase, step up your efforts to monitor for thrips, which vector impatiens necrotic spot virus (INSV). Cornell University floriculture specialist Nora Catlin and Rutgers Cooperative Extension agricultural agent Jim Willmott reported that INSV was detected on spring crops of Reiger begonias and diascia.

Look for ringlike spots, irregular necrotic spots, brown stem lesions, stunting or other symptoms that can’t be attributed to other causes.

If plants are diagnosed with either INSV or tomato spotted wilt virus, remove and destroy them.

For more: Jim Willmott, (856) 566-296; http://njaes.rutgers.edu/pubs/fipmnotes.

TMV and iron deficiency. Tobacco mosaic virus symptoms can be confused with iron-deficiency symptoms, reported Tina Smith and Doug Cox at University of Massachusetts . Iron deficiency symptoms generally show up as interveinal chlorosis, normally starting at the shoot tips, but often occurring throughout the entire plant. Sometimes the leaves of iron deficient plants turn almost white.

TMV symptoms appear as yellow and green mottling, upward leaf curling, leaf distortion and overall stunting. Susceptible plants include bacopa, calibrachoa, scaevola, snapdragon and petunia.

Prevent iron deficiency by controlling pH (maintain growing medium pH of 5.5-5.8) and using iron-chelate fertilizers. Don’t apply chelated iron-containing fertilizers to iron sensitive plants including geranium, marigold and other crops that are sensitive to iron and exhibit iron toxicity symptoms.

For more: Tina Smith, (413) 545-5306; www.negreenhouseupdate.info.

CDFA detects white rust. On Feb. 14, California Department of Food and Agriculture confirmed the detection of chrysanthemum white rust, Puccinia horiana P. Henn., on field-planted mums at a San Diego County cut flower nursery. This is the third CWR detection at this production site.

As a result of this latest detection, USDA issued an Emergency Action Notice on Feb. 16. Approximately 4,000 mum plants were destroyed.

On Feb. 27, CDFA also made an initial detection of CWR in an outdoor mum field at a cut flower nursery in Santa Barbara County . This detection was confirmed by CDFA and a USDA EAN was issued on March 1. This field had been harvested in mid-October to November 2006. National CWR Management Plan for Exclusion and Eradication was being followed for both detections. The impacted nurseries only sold product locally.

{sidebar id=1}

For more: Division of Plant Health and Pest Prevention Services, Department of Food and Agriculture; (916) 262-1100; www.pestalert.org.