Relationship Between Flower Visitors and Cotton Hardlock Breno Leite, Jim Marois, David Wright, Enoch Osekre and D. J. Mailhot University of Florida, Quincy, FL Relationship Between Flower Visitors and Cotton Hardlock Breno Leite, Jim Marois, David Wright, Enoch Osekre and D. J. Mailhot University of Florida, Quincy, FL Beltwide Cotton Conferences, 2007

HealthyHardlocked Open Cotton Bolls Locks fail to allow fiber outward expansion Do not fluff out Beltwide Cotton Conferences, 2007

Hardlock causes yield losses ranging from % Harvested Rows Beltwide Cotton Conferences, 2007

Associated with infection by Fusarium verticillioides through the flowers Most severe along Gulf Coast and is a major limiting factor of Florida cotton yield Flower thrips and bumblebees are likely to be contributing factors for infection and Fusarium dispersal (will be discussed in another presentation*) *3:30 PM 01/11/07 Relationship Between Flower Visitors and Cotton Hardlock, B. Leite, J. Marois, D. Wright, E. Osekre and D. J. Mailhot Hardlock Beltwide Cotton Conferences, 2007

Figure 2 – Image analysis (Software Image J – NIH) to estimate fiber density in a determined area. Device designed to facilitate fiber count per area (A). Typical healthy fiber density (B). Typical hardlock fiber density - type 4. Close view suggests that there is debris deposited in between the fibers (C). A healthy cottonseed (H) with a diseased cottonseed, hardlock – type 4 (D).

Beltwide Cotton Conferences, 2007 Figure 3 – Relationship between density (% fiber per area) and cottonseed weight. Healthier locks consistently exhibit higher seed weight and less fiber density (ideal for picking). In contrast, seeds from bolls with hardlock (type 3 and 4) have lower weight and high fiber density (not harvestable).

Beltwide Cotton Conferences, 2007

* Hardlock of cotton seriously affects yield in many areas of the southeastern United States, and can be devastating in the panhandle of Florida. * In 2002 it caused over $20,000,000 in lost yield, reducing Florida’s average yield from 650 lb/acre to less than 400 lb/acre. * Hardlock is more severe when there is: High nitrogen High plant density High temperature and humidity Insect damage Seed rot

Beltwide Cotton Conferences, 2007 General: Characterize the casual agent of the disease and to develop effective control measures against the disease. Specific: Find the principles of disease establishment. Follow step by step the pathway of Fusarium conidia germination. Find out why some control measures fail or failed in past years. Our Objective:

Beltwide Cotton Conferences Traditional boll rots. Boll rots usually are the product of insect damage or pathogen activity after the bolls have opened or early in the season when the carpel turns brown or black and never opens. Boll rots occur during wet weather when the cotton boll or fiber is colonized by a number of pathogens, although only a few fungi are responsible for the majority of infections. These include Alternaria gossypina (Thuem.) Hopkins, Curvularia spp., Diplodia gossypina Cke., Helmithosporium gossypii Tucker, Fusarium spp., and Phomopsis.

Beltwide Cotton Conferences, 2007 Thus far we have shown that the majority of hardlock is caused by the fungal pathogen Fusarium verticillioides, also known as F. moniliforme. This is the same organism that causes corn ear rot. We have shown that the main mode of infection is through the cotton flowers, and that fungicides applied to the flowers will control the disease. This is an entirely new approach to the etiology and control of the disease and in 2003 field plots are replicated throughout the southeastern states in an attempt to reproduce the results developed at the NFREC at Quincy. This has become a regional project with university faculty from Louisiana, Mississippi, Alabama, Georgia, South Carolina and Florida (NFREC and WFREC) working together, with major funding provided by Cotton Incorporated.

Beltwide Cotton Conferences, 2007

Results above represent typical results obtained by testing water extracts from Fusarium cultures growing on acidified Potato Dextrose Agar (aPDA) and extracts from healthy and hardlocked samples (type 1, type 2, type 3 and type 3). Most of the samples are negative for fumonisin, except the extracts from fresh cultures. The reason why type 2 is sometimes positive (data not shown) for fumonisin is under investigation.

Beltwide Cotton Conferences, 2007