Bacterial speck of tomato is caused by the bacterium Pseudomonas syringae pv. tomato. Disease occurs when bacteria are deposited onto plants by splashing rain or irrigation water, on transplanting equipment, or through contaminated seed. Bacterial speck is favored by low to moderate temperatures (64-75ºF) and high humidity. P. syringae pv. tomato can be disseminated between fields in surface irrigation water, by wind as aerosols, and on contaminated equipment. The bacterial speck pathogen can survive on the surface and roots of weeds without causing disease symptoms, in crop debris (up to 30 weeks), and on contaminated seed. P. syringae pv. tomato survival in soil is short, generally less than 30 days.
Bacterial speck symptoms begin as small, round, dark brown to black lesions on leaflets. Lesions can occur throughout the entire leaf area, but are most prominent on the bottom sides of leaves. As lesions age, a halo develops around lesions. Oval to elongated lesions can form on stems, petioloes, peduncles, pedicels, and sepals. Dark brown to black fruit lesions are minute (0.04 inch or smaller), and often tissues surrounding the lesion are an intense green color. Lesions are usually slightly raised or flat when first observed, but can be sunken.
No biological control strategies have been developed for bacterial speck.
Plant only high quality seed and transplants known to be free from the bacterial speck pathogen. Use seed treatments routinely to reduce seedborne inoculum. Practice a three-year or longer crop rotation between tomato crops. Eliminate cull piles and weeds that can serve as a source of the bacterium. Plant resistant varieties if available. Apply adequate but not excessive nitrogen fertilizer. Avoid overhead irrigation and reuse of irrigation tail water.
Resistance to copper bactericides is widespread in the bacterial speck pathogen. Tank- mixing copper bactericides with EBDC fungicides such as maneb can provide some suppression of copper tolerant strains of P. syringae pv. tomato. The plant activator Actigard can provide effective control of both copper sensitive and tolerant strains of P. syringae pv. tomato. Chemical controls are most effective only combined with as many cultural controls as possible.
Product List for Bacterial Speck:
Pesticide |
Product per acre |
ApplicationFrequency
|
Remarks |
|
Acibenzolar |
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|
Actigard 50 WG |
0.33-0.75 oz |
7-14 days |
Do not apply to stressed plants; Start applications at a low rate and slowly increase; Maximum of 4 ounces per season; 14 day PHI |
|
Copper Fungicides |
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|
Champ Dry Prill |
1.33 lb |
5-7 days |
|
|
Champ Formula 2 |
1.33 pt |
5-7 days |
|
|
Copper-Count-N |
4-6 pt |
7 days |
|
|
Cuprofix Disperss |
2.5-6 lb |
7-10 days |
|
|
Kocide 101 |
1.5-3 lbs |
5-7 days |
|
|
Kocide DF |
1.5-3 lb |
5-7 days |
|
|
Kocide 4.5LF |
1-2 pts |
5-7 days |
|
|
Kocide 3000 |
0.75-1.75 lb |
5-10 days |
|
|
Nordox |
1.5-2.0 lb |
7-10 days |
|
|
Tanos |
8 oz |
5-7 days |
Suppresion only; Rotate with fungicides with a different mode of action such as chlorothalonil or mancozeb; Maximum of 72 ounces per season; 3 day PHI |
|
Tri Basic Copper |
2-4 pt |
7-10 days |
1 day PHI |
|
Copper/EBDC/Zoxamide Mixtures |
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|
Cuprofix MZ Disperss |
1.75-4.75 lb |
3-10 days |
Maximum of 21 pounds per season; 5 day PHI |
|
Gavel |
1.5-2.0 lb |
7-10 days |
Maximum of 4 (west of Rockies) to 8 (east of Rockies) applications, 5 day PHI |
|
ManKocide |
2.5-5.0 lb |
3-10 days |
Maximum of 42.7 pounds per season; 5 day PHI |
|
Famoxadone/Cymoxanil |
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|
Tanos |
8 oz |
5-7 days |
Rotate and rotato with fungicides with a different mode of action such as chlorothalonil or mancozeb; Maximum of 72 ounces per season; 3 day PHI |
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The information herein is supplied with the understanding that no discrimination is intended and that listing of commercial products, necessary to this guide, implies no endorsement by the authors or the Extension Services of Nebraska, Colorado, Wyoming or Montana. Criticism of products or equipment not listed is neither implied nor intended. Due to constantly changing labels, laws and regulations, the Extension Services can assume no liability for the suggested use of chemicals contained herein. Pesticides must be applied legally complying with all label directions and precautions on the pesticide container and any supplemental labeling and rules of state and federal pesticide regulatory agencies. State rules and regulations and special pesticide use allowances may vary from state to state: contact your State Department of Agriculture for the rules, regulations and allowances applicable in your state and locality. |
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Categories: Eggplant, Pepper, Tomato, Disease, Bacterial Speck
Date: 04/02/2007