Answer: Gladioli are relatively free of insect pests. The most troublesome pest is the gladiolus thrips. This insect is very small and seldom seen as it feeds in hidden places. It does considerable damage, especially to the flowers. It works on the buds before they emerge from the sheaths and causes malformed and spotted flowers. Thrips may overwinter on the corms. Aphids, grasshoppers and cucumber beetles are other insect pests that may cause damage to flowers or foliage. If you are finding worms, you can control them with Bt (sold as Dipel or Thuricide).
There are many different disease organisms that attack the corms and stems of the gladiolus. Collectively, they might best be called corm and stem rots. Most are active during storage and develop with improper curing and storage. Before corms are planted in the spring, they should be carefully inspected. Pull back some of the husk to examine the inner surface and eliminate all corms that are infected. Although infected bulbs may grow if planted, growth is generally weak and stem rots often develop later to cause death. One of the best control measures against these rots is immediate removal and destruction of bulbs or plants that show disease.
I think it would be easier to simply replace the glads by purchasing fresh new corms next spring and planting them in a different spot in the garden. Hope this information is helpful.
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