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Editor's Note: This column was provided by Purdue University's Extension Service. Columnist B. Rosie Lerner is a consumer horticulturalist. Here she answers two questions provided by Hoosier gardeners.
I have two large pecan trees that have a problem. One tree is 75 feet tall with a 30-foot spread. The other is about half this size. Both trees were started with nuts. Both produce large quantities of nuts that do not mature.
When the nuts get to the kernel stage, the insides dry up, and the nuts fall off. The trees get plenty of water and fertilizer from the yard, so I can't figure out what the problem might be. Can you tell me what my problem might be? I hate to see all these nuts go to waste.
Answer: Although there are a number of insect pests and diseases that can cause crop failure, what you've described is likely a lack of kernel development due to inadequate pollination.
Pecans require cross-pollination to set and mature the nut kernels. Since these two trees were started from seed, it is impossible to know their pollination compatibility.
Also, there are Southern pecan types, which are not fruitful this far north, and Northern pecan types, which are marginally hardy in your area.
To improve your chances for pecan production, it is critical to start with planting stock of Northern cultivars. Generally one from each of the following Northern "groups" is needed for cross-pollination. Group I: Giles, Major, Peruque and Group II: Colby and Posey.
Pecans are only marginally hardy in your area, so it could be a long shot to invest in additional pecan trees. Even in a protected location, it will likely be 5-8 years before they become mature enough to fruit.
Question: I returned to gardening this past season and planted about 10 green bell pepper plants along with banana, cayenne and jalapeño peppers. All the peppers did well except for the bell peppers. We harvested nothing from the bell peppers.
We had many blooms and the plants grew to a good size, but no fruit. Sometimes we thought these plants looked a little "burned," as if the plant had too much fertilizer; however, we did not fertilize this year. Just wondering if you think we have a problem with the plants, pollination or the pH of the soil? I should also note that our new garden resides in a former hog lot, so I am suspicious that the soil is in disagreement with the bell pepper plants. Any advice?
Answer: The "hog lot" soil may have been a bit high in nitrogen, though if the other plants were not affected, I would not suspect this to be a soil or excess fertilizer problem. It is possible that the soil is not uniform and could have some "hot spots" of composting manure that may have caused a bit of foliage burn.
However, I think you're right to suspect a pollination issue. Bell peppers have a fairly narrow temperature range at which they will set fruit. Last summer's temperatures were not very good for bell pepper production, so a lot of gardeners complained of poor pepper production.
The optimum temperature for bell peppers is 70 to 75 degrees, while the optimum for hot peppers is 70 to 85. Bell pepper flowers are likely to drop without setting fruit if temperatures climb above 85 degrees or drop below 60 degrees. Let's hope for better conditions this season.