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Causal Agent: (fungus ‑ Fusarium oxysporum f.sp. niveum)
Initially,
leaves of infected plants wilt during hotter times of the day, but eventually,
the wilt becomes permanent [wmd45.jpg].
Initially, one or a few vines of a plant are affected, but eventually
the other vines wilt and the plant dies. Other
agents can cause plants to wilt. For example, anasa wilt is caused by the feeding
of the squash bug.
The fungus
causes browning of the xylem (water-conducting tissue) of the crown and runners
[wmd46.jpg].
Races 1 and 2 of this fungus are present in several watermelon-growing
areas of Texas. Most commercial cultivars have resistance to
to race 1, but not race 2. The fungus persists many years in soil and so, watermelons
should not be replanted into infested soils for at least five years.