USA
May 8, 2019
Understanding the significance of a disease
A successful breeding program relies on communication with local growers. Enza Zaden works hard to listen and learn from local demand to develop varieties that can improve production cost. Today, high yield is no longer enough - varieties have to also be uniform in fruit shape and size, hold a good shelf life and be resistant to widely occurring and emerging diseases. These factors were driving us to generate a tomato variety such as Winterhaven.
Winterhaven is a variety with an outstanding disease resistance package-which sets the hybrid apart from the competition. Among the resistances that it has, Winterhaven showed a high level of Tomato Yellow Leaf Curl Virus (TYLCV) resistance, which has been a devastating and widely occurring tomato disease in the Florida and Georgia areas.
What is TYLCV?
TYLCV is transmitted by adult silverleaf whiteflies and can spread rapidly in tomatoes. Symptoms of a TYLCV-infected tomato plant include; stunting, leaf curling, and yellowing. This disease can have a severe impact on a grower’s tomato production – plants infected at an early age will not bear fruit due to flower abortion and growth will stop. Host plants include peppers, tomatoes, sow thistle, cheese weed and nightshade weeds.
TYLCV is a complex disease caused by different geminiviruses. According to Enza Zaden Tomato Breeder Jeremy Sisson, the pathogen is constantly changing and evolving which requires Enza Zaden breeders to continue to improve the resistance level of varieties. This pathogen persists in Florida and Georgia areas because of the following reasons:
- The areas have mild winters, which enables the insect to over-winter in weeds and host plant species. When the insect life cycle is not interrupted, the pathogen accumulates over time.
- White flies can be resistant to traditional sprays, so sprays have become less effective. Because growers cannot control the vector transmitting the virus, the virus has grown into a larger problem.
Resistance and other benefits of Winterhaven for growers
TYLCV can cause up to 100% yield loss. Understanding the significance of the disease, Enza Zaden incorporates the resistance as a “must have” resistance in our commercial hybrids developed for Georgia and Florida growing areas.
Winterhaven is a variety that is adapted in Florida for the production slot/planting time (end of November to mid-February). While most available commercial varieties produce flat fruit shape during this slot, Winterhaven maintains a consistent round shape that is suitable for slicing tomatoes.
Additional resistances in Winterhaven
The Winterhaven variety is also resistant to other major diseases including:
- Fusarium wilt race 3: A widespread disease in US southeast regions that can cause complete yield loss. Disease symptoms include vascular discoloration, leaf yellowing and wilting on one side of the plant followed by complete loss of a vine or the whole plant. Having a resistant variety to Fusarium wilt race 3 is important because growers have less options for effective fumigants; genetic resistance is now the best means to control this pathogen.
- Tomato spotted wilt virus: The symptoms of this virus include necrosis on the new growth, stunted plants and dark streaking on the stem. The fruit may be deformed or wilted, with a reduction in fruit quality (due to circular browning pattern) and yield. Resistance to this virus provides growers flexibility to grow Winterhaven in multiple regions such as, Georgia, North Carolina, and Tennessee.
- Fusarium crown and root rot, symptoms include stunted growth and leaf yellowing that progress to wilting and dying. This resistance is mostly useful for the southeast Florida area where the disease is more prevalent.
Data information and illustrations in this presentation shall correspond as closely as possible to tests and practical experience. This information shall be provided to assist professional growers and users, whereby variable local conditions must be taken into account. Under no circumstances shall Enza Zaden accept liability based on such information for deviating results in the cultivated product.
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