Tar Spot: An Understudied Disease Threatening Corn Production in the Americas

Tar spot of corn has been a major foliar disease in several Latin American countries since 1904. In 2015, tar spot was first documented in the United States and has led to significant yield losses of approximately 4.5 million t. Tar spot is caused by an obligate pathogen, Phyllachora maydis, and thus requires a living host to grow and reproduce. Due to its obligate nature, biological and epidemiological studies are limited and impact of disease in corn production has been understudied. Here we present the current literature and gaps in knowledge of tar spot of corn in the Americas, its etiology, distribution, impact and known management strategies as a resource for understanding the pathosystem. This will in tern guide current and future research and aid in the development of effective management strategies for this disease.

Pregnancy rates following frozen embryo transfer (ET) in women failing to conceive despite fresh ET in women using low dosage follicle stimulating hormone (FSH) protocol for follicular maturation of several eggs

PURPOSE

To determine the pregnancy rate following frozen embryo transfer using embryos derived from low dosage follicle stimulating hormone (FSH) stimulation protocols in women aged < 42 who did not have diminished egg reserve as evidenced by a day 3 serum FSH < or =12 mIU/ml.

METHODS

A retrospective review was performed evaluating pregnancy rates on frozen embryo transfers from women who usually had diminished egg reserve and thus used no more than 150 IU of FSH. The pregnancy rates were calculated on the first frozen embryo transfer of women failing to successfully conceive on the fresh embryo transfer.

RESULTS

The clinical and live delivered pregnancy rates per transfer were 33.3% (14/42) and 23.8%. The implantation rate was 20.0%. Thirty-one percent of the transfers were in women aged 40-42.

CONCLUSIONS

These data show that despite the fact that with minimal stimulation protocols, the remaining frozen embryos are of lesser quality because of de-selection, nevertheless, it is worth transferring these embryos.